Have been asked by three different groups about dedicated lunar landers that could be developed leveraging a qualified crew vehicle.

Obviously one could include Orion and/or Dreamchaser into this as well, but those don't seem like likely candidates due to cost, weight, applicability.

This gets back to an early sixties study on deriving from Apollo, Gemini, and Mercury landable vehicles - the idea is to reuse the qualified systems that so much work went into for HSF. And, remember, the Apollo CSM had the propulsion to lift both off the surface for a direct return!

So, consider if one were to "piggyback" existing programs with say a $2B funding each optionally to increase to accelerate a) CCP completion such that crews are actually accumulating flight history on the vehicle, and b) derive an expendable lander, launched to LLO by commercial launch services, meant to dock with say Block 1/1B SLS launched Orion? Would also involve a checkout flight within two years - perhaps launched to the ISS autonomously, where a qualified pair of astros would undock, checkout the vehicle extensively, and then redock.

So we're talking of omitting the top aeroshell, just thin metal like the LM, converting the abort engines into descent/ascent engines, no heat shield, join SM/trunk to capsule and use volume as tanks/storage as with the LM, and add/reposition legs. And adding high-gain comm, and high visibility landing capability to piloting positions.

Oh, and you'd need a trainer. Cannabalize DragonFly?

In doing my sims, you'd have to significantly reduce mass, like with LM, to make this work. Oh, and the entry doors are too small for lunar egress/ingress. And I doubt the avionics are setup to allow depressurization/repressurization.

Is this a plausible program "option" to add?

Recap - for this thread, you can only do Dragon 2/Starliner, only launched to LLO, only launched on non-SLS, and largely(70-80%) of CCP qualified components. Optional points if you get a lander that could be evolved into a refuelable from SLS-launched "added" payload.

add:Oh and for the SuperDraco's let's assume either fixed pointing down launched in shroud or that tilt out for zero cosine losses. Optional higher expansion nozzle for more iSP.

add: Now that Musk has let the cat out of the bag, you can see that there is a place for this thread as one CC provider is announced as doing missions around the Moon.

The same propulsion pallet for Dragon/Starliner lander, discussed in this thread, could also be used as a means to enter/exit LLO, the next step past a free return.

So yes, I really mean it that this is about real hardware for real missions in the immediate future.

add:

Some additions. Regarding meaning of expendable or reuse:

For expendable, single use:

Surface access for multiple, suited astros for a 1-4 day access. Fully expendable single sortie.

And for reuse:

Same CC derived vehicle used for at least two sorties - LLO to surface to LLO is a sortie, even to the same place.Likely replenishment between sorties, replenishment from another vehicle than the lander.

add:No discussion of non-LLO mission architectures at all, take them elsewhere.

For this thread we'll focus only on a favorable to landers/surface exploration polar frozen LLO that is difficult to enter/leave/maintain - discussed mid thread. There are multiple variations within the margin of this mission architecture. The point is to put the burden on the earth crew vehicles for LOR (Orion/SLS has this already, CC vehciles could add it with multiple launch), we want to minimize lander operational burden (props, trip time, comm to surface, vehicle turnover,...), and allow an option for rapidly reusable lander with mission lifetime of around a month (focus on concentrating surface access capability through reuse).

So expendable lander can happen soonest, and reusable lander can demonstrate enhanced exploration as immediate benefit, besides increasing mission safety/contingencies through reflight. Later duration and/or concentration of reuse through performance enhancement can increase scope of use either to a single or multiple sites.

As well as avionics and controls the cabin will need life support. The ISS life support is too big and using Russian life support too controversial. Within 2-3 years test life support will be in the Dragon 2, Starliner and NextSTEP-2 Deep Space Habitats from Bigelow, Boeing, Lockheed Martin and Orbital ATK. One of these could be used as the cabin's life support.

Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip. Also meets criteria of a future, reusable lander.

The canted engines on Dragon 2 might not be so disadvantageous if they are providing the final landing control of the stack. Trunk mounted engines for the caspule/return would still be required.

I'd like to make a more thorough post with some analysis but don't have the time at the moment.

- modified versions of this can place heavy cargo payloads on the lunar surface.- modified versions of this can use other launchers for the tankers.- modified versions of this can use other means to get fuel into LEO.- future version could produce LOX on the lunar surface.- the tankers could be launched by SLS, in which case we have 1 launched to LEO to refuel the D2 stack there and/or another launched to LLO for the second refueling (I don't see how this could be cost effective).- Alternatively, the D2 + trunk + MUS could be launched by SLS to LLO (MUS does insertion burn) and then refueled from a tanker launched on a second SLS (again I don't see how this could be cost effective).

- This develops refueling capability, could use a shakedown mission in Earth orbit and/or lunar flyby, not much point in sending the stack to ISS (and probably would not be allowed anyway). Crew stays with D2 the entire time, and can use D2 abort capability at launch and retropropulsion landing.

This would I think have a low development cost (well under $2B) and per mission costs in the order of $700M. Using SLS would increase per mission costs to at least $1500M

Unfortunately, it does not quite meet the brief. Fuel rich architectures really hurt SLS because it costs so much to launch. To make this architecture work a high flight rate for FH would be required, and ideally from 2 launch sites, IF SpaceX could demonstrate 2 week turnarounds and use 2 launch pads. A design like this would place the D2 a long way above the ground, not exactly easy for egress.

2. Component reuse, new engine

- Don't reuse any structure from D2 or the trunk- Instead reuse components and subsystems.--- avionics--- ECLSS--- power and cooling- optimise design for mass.- use storable propellants and a new engine in the Draco family optimised for the mission.--- optimised engine probably cost effective as it makes the rest of the design easier.- two stage--- descent stage--- ascent stage, includes trunk functionality

- descent stage could be used as a cargo lander- ascent stage + crew compartment could be reused- storable propellants could be transferred to LLO on a commercial contract.

Once you decide to do away with most of the D2 structure, you might as well get rid of it all and start from scratch. It is difficult to reuse components and subsystems as is, there will be a constant pressure to modify them for performance, but that would almost certainly blow the budget. A tanker spacecraft would still be required, this time holding storable propellants. It is going to be difficult to do the development in the $2B budget. Development schedule just about impossible to get anything flying in 2 years. Missions will cost ~2B because of SLS+Orion+lunar lander+tanker+commercial launch.

Taking the TEI propellant from LLO all the way to the Lunar surface and back to LLO is a huge penalty since it requires 4 km/s of delta-V. Better to leave the TEI propellant in your tanker and have the D2+trunk+MUS dock with the tanker after liftoff from the Lunar surface.

Taking the TEI propellant from LLO all the way to the Lunar surface and back to LLO is a huge penalty since it requires 4 km/s of delta-V. Better to leave the TEI propellant in your tanker and have the D2+trunk+MUS dock with the tanker after liftoff from the Lunar surface.

Sure, but it avoids a rendezvous, docking and fuel transfer. Refueling the stack totally in LEO is also not optimum, better to send a full load of fuel on the tanker. So we might have:

Development program could have a Grasshopper like demonstrator. Showing the Modified Upper Stage (MUS) with trunk and D2 on top, performing various hops, harzard avoidance (not necessary in my opinion when landing on a prepared site). I think this could be done within 18 months of program start.

Development program would also need a fuel transfer in LEO demo and a long duration fuel storage demo. These could be done within 2 years of program start and be combined into one two launch demo (uncrewed). After 6 months in orbit the MUS could then perform a TLI.

A crewed Apollo 8 redux. could happen about 3 years into the program, with a cargo landing also in year 3 and then a crewed landing in year 4.

D2 would probably need a few modifications, but all relatively small. The communication system probably would need enhancement, software would need enhancement for controlling the D2 + trunk + MUS stack, hatch is probably too small (would need determination of what lunar suits would be used to be sure).

A major problem is landing on the moon using the Merlin 1D vac is likely to damage the engine due to flying regolith. There are three potential solutions I can think of:

1. Shut down the Merlin 1D vac early, then descend the last few hundred meters on Super Dracro.2. Prepare a landing pad in advance using sintering or perhaps laying a membrane.3. Protect the nozzle in some manner (or perhaps carry a replacement nozzle extension ?!).

I like option 2 the best as it would allow several landings in close proximity. It is more appropriate to a base, rather than a series of exploration missions to various landing sites.

Perhaps the Trunk could have a ‘Propulsion Pallet'tm mounted within it – 2x fuel, 2x oxidizer and 2x helium pressurization tanks; supplying a cluster of Draco thrusters (8 or 9) mounted in the center of the Pallet, or 1x Super Draco, throttled down and with or without a nozzle extension. Would it need about 2km/s delta v to insert into Lunar orbit and leave on an Earth transfer orbit X days later, or a bit more?The Dragon meets the LM Dragon waiting in lunar orbit, the crew transfers and then it’s time for P.D.I. (Powered Descent Initiation).

A Dragon Lunar Module: The trunk contains another Propulsion Pallet, but one with enough propellants and thrust to act as a virtual ‘Crasher Stage’ that is jettisoned before the ‘High Gate’ of the powered descent, allowing a Dragon LM – with no weighty Earth heatshield or parachutes – augmented with 4x strap-on or ‘saddlebag’ propellant drop tanks to descend to the landing site. After landing, 2x of the drop tanks are depleted and removed to discard dead weight. After the surface mission, the Dragon LM ascends via the remaining drop tanks prop supplies, plus internal propellants to the waiting Dragon CSM.

This is a variation of what I’ve proposed before with Space X-based launchers and spacecraft. Although, it could be a little more launcher agnostic. The two spacecraft could be orbited by Falcon 9 ‘Full Thrust’ expendables. Then, either Falcon Heavy reusable could send up a LOX/Kerosene second stage for the space craft to dock with and perform Trans-Lunar Injection, or Atlas V-552 could place a dual-engined Centaur into orbit near the spacecraft for the same procedure.

A variation of all the above could be done with a heavily modified Boeing Starliner as the CSM and the LM could be a bare-bones, clean sheet Commercial Space craft.

Another option for a bare-bones lunar mission with Dragon, would be to carry an unpressurized lander like this one into the trunk. Possibly derived from the Morpheus lander that was tested a few years ago.

The nice thing about unpressurized landers is that they don't really become obsolete if you come back with something bigger. With a moon base they are a viable emergency evacuation vehicle or backup, and they have a useful niche as hoppers to explore places that are a nontrivial distance away from the base or difficult to reach because of cliffs. Double the thrust and they could be useful on Mars as well.

Alternatively, if you had an ITS in orbit around the moon that could refuel a small unpressurized methalox lander, you could do something like a hundred sorties before having to refuel. Great for surveying a wide number of sites quickly.

For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v. Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here?

Capability. Dragon 2 / Starliner unmodified can't even make ascent to LLO with margin, so you already know you'll need to significantly improve propulsion, even if you were to use 1 vehicle to land and a different vehicle to ascend (assumes precision landing capability) - the absolutely simplest approach possible!

But even for that, at a minimum, you need an area ratio increase on engine nozzles of >10x, burn duration >1.5x, and tankage increase of 3x. The 2.5x more allows you to reach efficiencies near that of a single vehicle w/o modifying capsule systems/CG.

However, to do this, you must, like the LM, reduce mass and launch under a fairing (in this case a standard PAF). Which is off the shelf.

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A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip. Also meets criteria of a future, reusable lander.

Not suggesting returning capsule to earth, just to LLO. Again, the point here is proven systems, in this case hypers as potential refueling is already proven, and one can incrementally work up such a system to long duration, multiple sortie/mission reuse/disposal incrementally, deployable in a few years.

Hydrolox fuel transfer is still low TRL, (hope to see Altius coupler today - Hi Jon), and IVF is in the 1-3 years before first flight (still not committed to). Masten is tied up with XS-1, Xeus is to test with a discarded RL-10 for cost reasons and is a long way to flight test, let alone HR. Bridge too far.

ULA's long term vision is interesting. But at current rate of program speed (even with 0.5B of that $1B per vehicle in OP), it's still more than a decade away by my watch.

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The canted engines on Dragon 2 might not be so disadvantageous if they are providing the final landing control of the stack. Trunk mounted engines for the caspule/return would still be required.

The benefits for keeping the side mounts are a) keeps vehicle CG as designed, meaning that it does not need to be seen as a differently operating vehicle, b) lower to ground - you could build access into the trunk side as a fixed ladder etc.

- modified versions of this can place heavy cargo payloads on the lunar surface.- modified versions of this can use other launchers for the tankers.- modified versions of this can use other means to get fuel into LEO.- future version could produce LOX on the lunar surface.

- the tankers could be launched by SLS, in which case we have 1 launched to LEO to refuel the D2 stack there and/or another launched to LLO for the second refueling (I don't see how this could be cost effective).- Alternatively, the D2 + trunk + MUS could be launched by SLS to LLO (MUS does insertion burn) and then refueled from a tanker launched on a second SLS (again I don't see how this could be cost effective).

Any time you mess with SLS, you slow down both programs. Don't do it!

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- This develops refueling capability, could use a shakedown mission in Earth orbit and/or lunar flyby, not much point in sending the stack to ISS (and probably would not be allowed anyway). Crew stays with D2 the entire time, and can use D2 abort capability at launch and retropropulsion landing.

Way more than even SX ambitious. It's really a way to avoid the big rocket.

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This would I think have a low development cost (well under $2B) and per mission costs in the order of $700M. Using SLS would increase per mission costs to at least $1500M

And ... out of scope. And your test program alone would be about $6B.

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Unfortunately, it does not quite meet the brief. Fuel rich architectures really hurt SLS because it costs so much to launch. To make this architecture work a high flight rate for FH would be required, and ideally from 2 launch sites, IF SpaceX could demonstrate 2 week turnarounds and use 2 launch pads. A design like this would place the D2 a long way above the ground, not exactly easy for egress.

I'll given you points for attempting to build a lunar exploration program out of F9US taken to the max.

But that wasn't the OP. And the reason why the OP was written so, was to translate BOTH CC VEHICLES into a DEDICATED LUNAR LANDER w/o requiring integration with SLS/Orion - they all fly using own systems to LLO, dock, and complete mission segments separately. Optional long duration/refueling transfer much later.

Perhaps the Trunk could have a ‘Propulsion Pallet mounted within it – 2x fuel, 2x oxidizer and 2x helium pressurization tanks; supplying a cluster of Draco thrusters (6 or 8?) mounted in the center of the Pallet, or 1x Super Draco, throttled down and with or without a nozzle extension.

Not a bad idea.

It could be used in place of either extending tankage into the trunk (to shorten dev time and maintain commonality with Dragon 2. Could be jettisoned using the same cargo payload brackets before landing, like a "crasher stage".

Then you could use over-expanded, verticalized SuperDracos on the capsule to orbit.

A similar arrangement using stacked SM's on the Starliner, launched also in a fairing with a mass reduced outer skin and thrust structures might also give the same capability.

The advantage of launch under a fairing for both approaches is that you can have things like fixed landing legs, additional PV panels, high gain antenna's, and other booms. This greatly improves both development time and lander performance on LLO.

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Would it need about 2km/s delta v to insert into Lunar orbit and leave on an Earth transfer orbit X days later, or a bit more?The Dragon meets the LM Dragon waiting in lunar orbit, the crew transfers and then it’s time for P.D.I. (Powered Descent Initiation).

You're again forgetting that this is a dedicated lunar lander. See thread title. Read OP!

All the derived CC vehicle is doing is functioning as the LM did for Apollo. Orion is still the crew's ride!

add:

Outside of the AJ10 and derivatives, there is a need for qualified hypergolic engines for both concepts.

My concern is that SX/Boeing are not up to the task of appropriate lunar lander propulsion here. Convince me otherwise please.

You post above is epic and covers all the details - thank you. I too think a dedicated Lander is needed. Starliner under most any circumstances is not going to 'cut the mustard'. I only mentioned a Dragon Lunar Lander because I'd used those details in a couple other threads and included the details here, mainly for comparison.

I know that Northrop-Grumman was tapped by Golden Spike to design a basic, 2x person Lunar Lander. Some sort of derivative of this design might still be fairly close to what's required.

Outside of the AJ10 and derivatives, there is a need for qualified hypergolic engines for both concepts.

My concern is that SX/Boeing are not up to the task of appropriate lunar lander propulsion here. Convince me otherwise please.

Then who is? AeroJet Rocketdyne? I would argue that the primary american rocket engine development expertise now *firmly* resides at SpaceX and Blue Origin. For both cryo and hypergolic engines. Both have developed several high performance engines in the last decade, and on a small budget.

AeroJet Rocketdyne is more of a caretaker of older technology at the moment. (RS-68 being their last real development, 15 years ago) And to get them to do anything, you need to back up a truck with hundreds of millions of $ at a minimum.

Dragon 2, Delta II US, and Castor 30A are all injected into LLO by 3 separate Falcon Heavy's. Complicated in orbit rendezvous of all 3 components would be required.Castor 30A would be an expendable FH flight, both D2 & DeltaII stage could see maybe side booster reuse.

I think here my dV numbers are probably not totally right as I don't have any allowance for orbital maneuvers.*Assuming of course my ad-hoc spreadsheet isn't totally flawed.

3 flights of FH with at least 3 center cores and 2 boosters being expended is probably getting pretty expensive (3 x $135M?) but I'm sure a lot of missions could be bought with money saved by developing a multi-billion dedicated lander. The Dragon 2 and Delta II Upper stage stack with payload mass 15,355 kg which is either at the limit or just barely above what a FH can do expendable. Might be possible to do in 2 flights.

** A Centaur with around 8,500 kg prop in LLO could get a D2 down and back again with the D2 performing the necessary landing and lift off burns, cutting the required flights down but a single Atlas 551 couldn't lift it there (max payload to escape = 6109kg, lunar would be lower). This actually works out to very similar prop load as would be required for a centaur crasher + delta II ascent stage.*** A Raptor powered Falcon Heavy Upper stage could probably also perform the task on FH with various levels of expendable cores depending on prop load. Just sayin'.

AeroJet Rocketdyne is more of a caretaker of older technology at the moment. (RS-68 being their last real development, 15 years ago)

What about J-2X? They have also been given the contract to develop RS-25E and are developing the AR-1.

J-2X didn't go so well, did it? Over budget/schedule, underperforming, and shelved. As for AR-1, they are spending minimal amounts while waiting for that truck of cash to arrive. I'm skeptical.

Obviously they CAN do engines, just not as well as others these days. They bought up and merged with every traditional liquid propulsion maker and have a culture of expecting to be the default engine choice.

That's what I was thinking! It's a real pity this engine isn't being used. But then again; some of the products of Project Constellation often get slammed, even when it's not entirely rational to do so.

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Yes, though since I've already talked about Dragon and Starliner as prospective Lunar Landers, I don't have much to add. Though, I would ask if anyone knows much about their crew life support systems? And therefore, what about performing EVAs from them?

« Last Edit: 02/23/2017 09:43 PM by MATTBLAK »

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J-2X didn't go so well, did it? Over budget/schedule, underperforming, and shelved.

Please provide a reference showing that J-2X was over budget/schedule and underperforming. That was not my impression.

I just wanted to respond to this to clear up this - but in the interest of keeping the thread on topic, we should continue this elsewhere.

Yes, looks like I didn't have that right, I guess I transposed CxP issues on to J-2X. But as far as budget issues, the scope of the engine significantly increased when the project morphed from being a J-2 upgrade to a virtually new engine. I have a recollection (which could be mistaken) that the project was sold as being a mush faster/cheaper than it turned out to be. That is all.

Same scenario as above but taking the Delta II US based crasher lander to all the way to the surface to be refueled, saving some Dragon 2 prop for initial ascent, landed lunar payload: 300 kgIn this scenario availability of more efficient but non man-rated cargo landers could deliver the necessary 6000kg of prop for a man-rated Dragon2 + ascent vehicle to return to Lunar orbit. A overall cost reduction could be seen here as a lunar base evolves.

Another option instead of using the AJ-10 (ISP=319s) is the Aestus upper stage engine, a pressure fed N2O4/MMH engine used in the Ariane 5G upper stage with an ISP of 324s. The big advantage here being common prop to the Dragon 2 lander to support refueling in a reusable lander. The turbo pump fed but not yet in operation Aestus II could further enhance capabilities of the system with an ISP of 340s.

Same scenario as above but taking the Delta II US based crasher lander to all the way to the surface to be refueled, saving some Dragon 2 prop for initial ascent, landed lunar payload: 300 kgIn this scenario availability of more efficient but non man-rated cargo landers could deliver the necessary 6000kg of prop for a man-rated Dragon2 + ascent vehicle to return to Lunar orbit. A overall cost reduction could be seen here as a lunar base evolves.

Another option instead of using the AJ-10 (ISP=319s) is the Aestus upper stage engine, a pressure fed N2O4/MMH engine used in the Ariane 5G upper stage with an ISP of 324s. The big advantage here being common prop to the Dragon 2 lander to support refueling in a reusable lander. The turbo pump fed but not yet in operation Aestus II could further enhance capabilities of the system with an ISP of 340s.

So in this scenario the multistage lander is still pieced together in LLO? Seems a bit of a stretch to what has been done to date.

Keep in mind you can have as long a trunk as you like, and integrate within that trunk propulsion.

And no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.

After you've built a mission architecture and vehicle off that, then we'll talk about refueling from excess capacity and storage on other vehicle.

Aestus is still current, and there are stages available with it. There are a few others also in and outside of the US that also can be used.

Here's the difficulty with trunk based propulsion integration - staying within the bounds of what you can and can't do.

You can integrate and fuel a pallet/stage separately. Then you encapsulate it in the trunk while integrating "Dragon 2 Lander" derivative vehicle. Then you encapsulate in fairing. Then you integrate payload on LV. Launch to LLO and await Orion. On landing, you can burn coaxially for descent and braking, then jettison BEFORE landing.

Similar for Starliner.

Anything that breaks this CONOPS won't work for this thread. And could never operate/test/be flown.

Oh, and for checkout with ISS, the pallet/stage is safed. It will be jettisioned/disposed after test and before redocking with ISS.

Another thing. Look at Apollo 9's checkout for the LM. Note the spacewalk back in the event of a docking malfunction. That is a test that can also be done at the station.

Also, one could perform the equivalent of the Apollo 10 by having two landers on LLO - one to simulate landing, then at the last moment abort and return on ascent engines. Following that, one could take the second and complete the landing. Then you'd have flight history before the initial landing.

And no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.

What launch vehicles would be allowed? Just commercial or a second SLS?

Without docking to a crasher stage in orbit, or some in space prop transfer, or high ISP cryogen propulsion I just don't see how a Dragon 2 (nevermind the heavier Starliner) could possibly work.

The Apollo Lunar Module was 15200kg total mass in Lunar orbit. The ascent vehicle was 2150 kg dry. That is about what a single FH can place in lunar orbit, meaning a crew dragon would need to lose 2/3 its mass operating as a 2 stage Lander/Ascent vehicle to fit those constraints

And no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.

What launch vehicles would be allowed? Just commercial or a second SLS?

Without docking to a crasher stage in orbit, or some in space prop transfer, or high ISP cryogen propulsion I just don't see how a Dragon 2 (nevermind the heavier Starliner) could possibly work.

The Apollo Lunar Module was 15200kg total mass in Lunar orbit. The ascent vehicle was 2150 kg dry. That is about what a single FH can place in lunar orbit, meaning a crew dragon would need to lose 2/3 its mass operating as a 2 stage Lander/Ascent vehicle to fit those constraints

A Dragon V2 made to land on the lunar surface with enough fuel to get back to LLO would likely come in at 45 metric tons.

Interestingly if you made a separate lunar vehicle with composites you probably could make a landing vehicle both lighter and roomier than the original LM.

SS1 minus it's wings probably could make lunar orbit and had a loaded mass of 3600kg with some extra propellant reserves I'd say 4000kg which means the entire lander would be 12,000kg.Which shows why they choose lunar orbit rendezvous in the first place.

Though for a lunar lander I'd use something like Xcor's 5M12 for landing and the XR-5K18 for the ascent propulsion.

Might be be able to make the lander single stage if the Falcon Heavy US is used as a crasher.

The price of a "crasher stage" is to eliminate reuse as a possibility, for the benefit of accelerating a development program. As both LEM/LM and LK-1 (derived from Soyuz and using a crasher descent stage) attest to.

There are studies for refuelable lander concepts. These combine ascent/descent phases with the same vehicle/engines and rely on more delta-v and high iSP engines/nozzles/propellant/tank volume that both Dragon 2 and Starliner don't possess with SuperDraco and Bantam engines used for abort. Which gets back to my "neither is up to the propulsion task" post above.

So you have two "rapid development" options - separate ascent/descent vehicles with precision landing, and ascent vehicle with crasher stage. Neither directly yields a reusable lander in LLO.

For that, you'd need larger delta-v, and because of the weight growth, more iSP to make it useful. Playing with a kerolox environment like SX has in abundance is a no-go, as they have not demonstrated the long lived and ultra reliable needs that traditional stored propellant already have.

However, if you design your mission architecture such that you can "phase in" moving to a reusable architecture, then you can prove with an expendible component for speed and then migrate to the reusable.

The key advantage of that approach is to flight prove ascent engine capability soonest, with the capability for descent as well, and then revise the ascent configuration to provide enough to allow both ascent and descent. Followed by a means to refuel from excess SLS capability, tanker, or other cargo capability.

The price of a "crasher stage" is to eliminate reuse as a possibility, for the benefit of accelerating a development program. As both LEM/LM and LK-1 (derived from Soyuz and using a crasher descent stage) attest to.

Not necessarily. The crasher stage in the scenarios I listed is only to provide for a two way trip, and could be eliminated by refueling the stacked Dragon capsule and ascent stage in LLO and lunar surface.

So reuse could be phased in as more capable vehicles get developed, but the concept listed gets the ball rolling on manned landers with minimal development cost. -Start with a single Dragon 2 and crasher trunk integrated stage to land a cargo/surface "lab" type of mission. -Initial manned missions use a LLO docked crasher descent stage to land a Dragon 2 & trunk integrated ascent stage this doesn't need to separate.- Follow up missions can refuel the D2 & ascent stage, along with a new crasher stage.-If regular lunar missions and a base were happening a more mass efficient cargo delivery system would need to be developed, and cargo would probably be far more frequent than crew. Long duration cryogenic stages like ACES would be ideal for this + ISRU.-With something like the ACES in operation the 6-7 mt of hypergol prop per ascent stage can be delivered to LLO lunar surface for cycling landers. Although an alternative would be to use an ACES as a "braking tug" from LLO. -After this point a cost/benefit analysis would need to be done to decide whether a new all cryo fuel manned lander would be worth the added cost of development.

I think that by tweaking the scenarios I proposed previously can probably get a single FH launch to place a Dragon 2 w/ fueled ascent stage in LLO. Such as: full N2O4/MMH architechure, rely on a little more cargo transfer from Orion, varying prop loads so the Dragon 2 does less of a landing burn at the Superdraco ISP (also include a small boost to ISP by larger nozzles) and perhaps using the Aestus II.

The price of a "crasher stage" is to eliminate reuse as a possibility, for the benefit of accelerating a development program. As both LEM/LM and LK-1 (derived from Soyuz and using a crasher descent stage) attest to.

Not necessarily. The crasher stage in the scenarios I listed is only to provide for a two way trip, and could be eliminated by refueling the stacked Dragon capsule and ascent stage in LLO and lunar surface.

Definitions here. A "crasher" stage is depleted on descent, has no props to land, and you discard/"crash" it well away from where you land, outside of debris cone (large due to low lunar gravity). It's sole purpose is to preserve the lander's props/engine for ascent.

So no, you don't reuse it. That's the whole point.

Secondarily as to "docking" or integrating on orbit a stage with the vehicle (I'm assuming something like Gemini/Agena) - integrating a stage is nontrivial, as well as docking it. The whole point of this is to minimize the complexity of the lander from a known, qualified crew vehicle.

Where it will get exciting is on precisely two fronts - propulsion and mass reduction. Like exactly with the LM.

Which is what I thought all the discussion would center on here.

Essentially, with modern materials that Dragon/Starliner use/can use - can we drastically reduce the weight even more than Grumman did with LM - which was the limiting factor in how soon the LM could "fly". Remember - neither Dragon nor Starliner need to have the same thrust structures and mass distributions, because they would be used entirely in space, in the lunar environment, for a short time with human occupants, and launched under a fairing.

For this, the LM had practically a metal foil for walls, it was basically a balloon.

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So reuse could be phased in as more capable vehicles get developed, but the concept listed gets the ball rolling on manned landers with minimal development cost. -Start with a single Dragon 2 and crasher trunk integrated stage to land a cargo/surface "lab" type of mission.

Dragon can already land on the moon. Ask Musk. No crasher stage needed.

I think you could also do this with Starliner if repurposed. Yes it would need to be lighter.

Nope. A nonstarter because of the need for multiple dockings with Orion, the fact that the stage could not arrive, or arrive and not be usable, or in the intervening time if autonomously "docked" lose capability before Orion arrives. Too many things to go wrong and too few contingencies.

A better plan is to use the components of a stage that fit within the trunk, perhaps on a pallet, that is integrated with the Dragon's flight systems for SC integrity/GNC/jettison. Since it would be minimally used for (likely) two burns - Powered Descent Initiation and Braking Phase / "High Gate", these axial burns only require the CG of the combined vehicle to thrust through, as opposed to the 6DOF needs of an independent vehicle operation!

So you have little idea of how much more complex things can get.

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- Follow up missions can refuel the D2 & ascent stage, along with a new crasher stage.

Nope - refueling architecture builds off of vehicle attachment and requires tankage in the supplying vehicle as well as excess payload mass. As an example of how this could work - Orion could dock with a module that would effectively be a docking tunnel of a minimal sort with a thrust structure to support tankage around it, and the CC derived lander would dock and accept fluids from ancillary docking extensions on the other end. Such would be extracted after LOI similar to the LM extraction of Saturn IVB, and initially docked with the CC derived lander vehicle for fluids transfer (note vehicle is unoccupied while fueling!), then undocked, discarded, and the CC derived lander would then redock for astro transfer.

This has the benefit of reusing all the capabilities already designed into the existing vehicles for later use unmodified.

And, note that it's a follow on. So scope doesn't creep.

Keep in mind this is meant as being entirely done and tested in a few years, not a few decades.

It is extremely hard to do HSF vehicles. Just minor mods require considerable work to be redone. This thread is an attempt to have extremely narrow scope to explore a real opportunity to do a real mission with real budget on a real time schedule.

So its a case of doing as little as possible, because even that could be too much.

Not playing rocket fabulist. There are plenty of threads for that here too.

Shouldn't landers/ascent vehicles be minimal for safety and cost? Like the size of the Soyuz descent module, maybe with more seats. A pre-landed uncrewed habitat (never to be launched from the Moon) within walking range could support them while on the surface. And another habitat in Lunar orbit for the transfers.

For sustainable presence on the Moon one should not launch more stuff than necessary from it, but accumulate landed useful mass there.

Shouldn't landers/ascent vehicles be minimal for safety and cost? Like the size of the Soyuz descent module, maybe with more seats. A pre-landed uncrewed habitat (never to be launched from the Moon) within walking range could support them while on the surface. And another habitat in Lunar orbit for the transfers.

For sustainable presence on the Moon one should not launch more stuff than necessary from it, but accumulate landed useful mass there.

A ground vehicle like the MMSEV able to take astronauts from the landing site to the village would mass 5-6 tonne. This can also be pre-landed.

During landing and take off spacecraft throw up a considerable amount of dust that will sand blast anything in range. Consequently the landing site and the habitats are likely to be in different craters.

I may be pushing the boundaries of Dragon or Starliner-derived lander here - so, SpaceGhost, if you feel I have, let me know and I'll delete my post.

Operating premise; keep costs down, including R&D. Use existing tech (Dragon2, in this case) as much as possible. That means, in part, keep it as simple as possible. It also means avoiding unneeded mass. It would require lunar orbit rendezvous like Apollo.

First, Dragon 2 needs a propulsion service module to enter and leave lunar orbit. (please bear with me here, as this is directly relevant to the lander design). Essentially, a cylinder, slightly smaller in diameter than the F9 (to fit within the Dragon trunk), containing Superdracos (2, for redundancy) and fuel. Theoretically, you should be able to make this with about the same mass ratio as the upper stage. It'll be a short cylinder, mounted behind the trunk, size dictated by needed delta/v and thus tankage capacity. Needed Delta/v is entering low lunar orbit and departing. So, what length and mass? To the rocket equation! A Dragon 2, plus trunk, plus crew, etc, reportedly (?) wet masses about 7385 kg. (In this scenario, the Dragon2 plays the role of the Apollo CSM stack).

The math. It takes about 680 m/s to enter low lunar orbit. About the same for the TEI burn. So, 1360MS. Round up for margins, 1500 m/s. ISP of a SuperDraco is about 240 at sea level. But, the fuel is MMH/NTO, which has a theoretical max of 336, so a superdraco with a vacuum expander bell (with electric actuators for steering) should do a lot better than 240. I'll ballpark it at 275, which I think is conservative. The dry mass of this upper stage should be, using a mass fraction of the S2 (again, I'm being conservative - this service module is just tankage and superdracos, and does not need to support Dragon and Trunk launch loads the way S2 does). Annnnd, ack, I can't find a mass figure, even a ballpark, for a superdraco. So, I'm going to totally ballpark it and take a SWAG, so basically my proposed service module for inside the trunk is a scaled down Stage 2 in mass fraction. S2 Dry mass (?) is 3900 kg. I'll scale that down, as the service module is a lot smaller, with fewer structural demands.

Dragon2 plus internal SD fuel, etc, has reported mass of 7385kg. I'll add 1000kg for crew plus non-life-support consumables, putting it as 8385kg. That, plus dry service module (I've rounded that up to 1000kg - a very poor mass ratio compared to either F9 stages), 9385kg. So, per the rocket equation, we have a fuel mass for the service module (to get 1500 m/s delta/v) of 7000kg. That's about 1555 gallons. Even assuming the same density as water, it should therefor fit in a cylindrical unit within the trunk.

So, the service module is a cylinder, 1000kg dry mass (It's far smaller than Stage 2, and I'm taking a wild guess as to SuperDraco mass), using 2 Dragon Superdraco engines. Here's where it finally gets relevant to this thread; It's also a baseline lander, derived in part from Dragon 2 components.

It'll need a few mods; add legs plus draco thrusters and Dragon avionics. Without cargo, by itself, it has a delta/v of 5.5 kps, more than enough to land on the moon and take off again (you need 4.4 kps for that.) It can carry 600kg of payload and still do the job (low lunar orbit, land, and come back). Crew accommodations would consist of lightweight aluminum tube Apollo style couches atop the cylinder (They're in space suits - no need for walls, life support, etc.). That same lander type, in one-way cargo mode, could land 2500 kg of cargo on the moon - for example a BEAM type module (With a dragon-based life support) for a short term hab, and other supplies. If added capacity is needed on the crew and cargo versions, it could be attained by stretching the tanks; it could land and take off with one superdraco even with an additional couple of tons of fuel, due to the low lunar G. (The stretched version could thus include a stowed expandable hab on the crew lander).

A mission might look like this; a FH launches with a lander plus cargo and a crew lander, either stacked or side by side in a shroud. These go to low lunar orbit. A third launch is a fuel depot - not technically hard, as the fuel is storeable hypergolic. 4th launch, crew Dragon plus service module. Rendezvous in lunar orbit. Crew handles docking plus topping up the two stages. Cargo lander lands the cargo - if successful, a crew descends on the crew lander, stays a few days, then ascends to rejoin Dragon for a return to Earth. Crew lander remains in low lunar orbit, to be refueled from the depot for the next mission. This architecture is flexible; could be used to set up a base, or have a standby emergency ascent vehicle.

Is this a bit far fetched, and relying on a lot of assumptions and guesses? Yup. I tried to be conservative, but I'm sure I missed some big things. I tried to keep it as cheap as possible, to make it viable for tourism. As part of this, I tried to keep it efficient (such as just couches on the lander, no structure or shell, and no staging, plus possibly reusable.)

A few huge technical challenges/issues; Can a FH push 16385kg (Dragon plus service module) through TLI? If they can, as claimed, throw 10 tons at mars, maybe, but my guess is probably not. If they do stretch the second stage, then I'd feel better about it being plausible. Another hard point is Lunar orbital rendezvous; hard to do. Can't use the GPS based system they use for ISS; GPS won't work in lunar orbit. The DragonEye laser docking system would - but navigation to close proximity will probably require either crew or a lot of work on the automated navigation system. Further problem, the fuel depot; storable fuel has been transferred in orbit before (such as to ISS) but I have no idea how hard it would be to accomplish for this.

I'm sure there are major flaws I didn't see - and I'd appreciate criticism and correction.

EDit: Here's one flaw I just found; I used 4.4 kps as the needed delta/v to get from low lunar orbit to the surface and back. It's not, it's 1.78 kps each way, so, 3.56 kps. All that means is I understate the cargo capacities above, and/or have more margin.

This would be a reusable lander: The lander consists of a stripped-down version of Dragon's pressure hull permanently mounted into a structural frame at the bottom. Set the lower part of the cabin into a frame that contains 2 banks of hypergolic propellant tanks (upper and lower banks) and lander legs. The lower bank of tanks provide propellant to Dragon's SDs for the descent and are dropped onto the lunar surface before ascent. The upper bank of tanks provide propellant to Dragon's SDs for the ascent burn and are dropped off in LLO after reaching it. Crew transfers back to Orion and goes home. Returning Orion for next mission brings fresh (full) tanks that are mated to the lander frame that was left in the stable LLO. Crew descends to lunar surface in this reusable lander and executes next mission. Will have to decide how many missions the lander is good for before it needs to be replaced.

Everything happens in a vacuum so we don't need clean lines. This will be ugly as hell but should work beautifully.

There would be no separate ascent or descent stage. Dragon IS the lander with a structural frame to contain and connect propellant tanks to her SDs. The frame is permanent. Only the emptied tanks are discarded. There would be no propellant "transfer" as brand new completely full tanks, brought along by the returning Orion would simply be connected to the plumbing.

This would be a reusable lander: The lander consists of a stripped-down version of Dragon's pressure hull permanently mounted into a structural frame at the bottom. Set the lower part of the cabin into a frame that contains 2 banks of hypergolic propellant tanks (upper and lower banks) and lander legs. The lower bank of tanks provide propellant to Dragon's SDs for the descent and are dropped onto the lunar surface before ascent. The upper bank of tanks provide propellant to Dragon's SDs for the ascent burn and are dropped off in LLO after reaching it. Crew transfers back to Orion and goes home. Returning Orion for next mission brings fresh (full) tanks that are mated to the lander frame that was left in the stable LLO. Crew descends to lunar surface in this reusable lander and executes next mission. Will have to decide how many missions the lander is good for before it needs to be replaced.

Everything happens in a vacuum so we don't need clean lines. This will be ugly as hell but should work beautifully.

There would be no separate ascent or descent stage. Dragon IS the lander with a structural frame to contain and connect propellant tanks to her SDs. The frame is permanent. Only the emptied tanks are discarded. There would be no propellant "transfer" as brand new completely full tanks, brought along by the returning Orion would simply be connected to the plumbing.

So this is a vertical lander then? Also it would need to be launched in a faring as you already know...

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.Fold the legs in - Apollo LM style for transport.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

The frame should be sized to fit inside the Trunk, opened at the top of course.The cabin would need a fairing to cover it for launch.

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

I always like reusable! You are going to need to replace the drop tanks after ever mission then?

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

I always like reusable! You are going to need to replace the drop tanks after ever mission then?

Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.

It's not pretty but it meets SpaceGhost's requirements in the OpEd on page 1 (I think). Now to do the math.

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

I always like reusable! You are going to need to replace the drop tanks after ever mission then?

Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

I always like reusable! You are going to need to replace the drop tanks after ever mission then?

Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.

Perhaps toroidal tanks could be mated without having to go EVA...

That works, but not 360 degrees all around. Hemispherical; 1/2 each of the required hypergol. One pair for the upper bank and 1 pair for the lower bank. Remember there's nothing in the middle. We can completely fill the space under the lander.

On second thought go all around with a single tank with a common bulkhead separating the 2 propellants. One for the upper load and one for the lower load.

Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.

I always like reusable! You are going to need to replace the drop tanks after ever mission then?

Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.

Perhaps toroidal tanks could be mated without having to go EVA...

That works, but not 360 degrees all around. Hemispherical; 1/2 each of the required hypergol. One pair for the upper bank and 1 pair for the lower bank. Remember there's nothing in the middle. We can completely fill the space under the lander.

On second thought go all around with a single tank with a common bulkhead separating the 2 propellants. One for the upper load and one for the lower load.

Dragon seats could be on a semi-circular track for take-off and landing and the display on a pivot if one wishes eyeballs out the window...

Apollo LM didn't have seats at all. The astronauts stood up. If mass is an issue they could do the same. Interior would not resemble the crew dragon very much. Very different mission profile, very different ergonomics.

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Dragon seats could be on a semi-circular track for take-off and landing and the display on a pivot if one wishes eyeballs out the window...

Apollo LM didn't have seats at all. The astronauts stood up. If mass is an issue they could do the same. Interior would not resemble the crew dragon very much. Very different mission profile, very different ergonomics.

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I may be pushing the boundaries of Dragon or Starliner-derived lander here - so, SpaceGhost, if you feel I have, let me know and I'll delete my post.

It's a fine post. On topic and relevant. I'll attempt to give you feedback.

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Operating premise; keep costs down, including R&D. Use existing tech (Dragon2, in this case) as much as possible. That means, in part, keep it as simple as possible. It also means avoiding unneeded mass. It would require lunar orbit rendezvous like Apollo.

Correct. And the existing tech also includes associated mission systems. Since docking is standardized, other vehicles that may be used like Orion have systems as well, but outside of such standardized interfaces, you don't "mix and match".

You do LOR because of the limitations of the combined systems. Each has a means to arrive on LLO. Adding complexity to share the ride slows things down. And you can use the excess performance margin for extended capabilities later. But it introduces risk, contingencies, and variables. Likely you want the CC derived lander on LLO ahead of crew launch, and thus it must last significantly longer.

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First, Dragon 2 needs a propulsion service module to enter and leave lunar orbit. (please bear with me here, as this is directly relevant to the lander design).

Wouldn't call it a SM. Dragon has an integral SM.

Would call it a jettison-able propulsion assist pallet (JPAP). Use the Dragon's trunk/radiator/other systems to keep PMF low, might construct CF tanks with integral thrust structure and membranes to get below F9US PMF.

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Essentially, a cylinder, slightly smaller in diameter than the F9 (to fit within the Dragon trunk), containing Superdracos (2, for redundancy) and fuel. Theoretically, you should be able to make this with about the same mass ratio as the upper stage. It'll be a short cylinder, mounted behind the trunk, size dictated by needed delta/v and thus tankage capacity.

Not how you do it.

You calculate your mission's needs, including contingencies venting etc, the length of engines/nozzles/gimbal freedom/recontact margin/jettison compliance/other. From these you get the overall tanks/pallet dimensions, size the trunk from that. Not the other way round. Oh, and I forgot, you need to add mission growth margin.

Then you can call it short, medium or long.

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Needed Delta/v is entering low lunar orbit and departing. So, what length and mass? To the rocket equation! A Dragon 2, plus trunk, plus crew, etc, reportedly (?) wet masses about 7385 kg. (In this scenario, the Dragon2 plays the role of the Apollo CSM stack).

Dragon lander is staying in LLO or being discarded. It is playing the role of LM + LOI, where if it is refueled it is just LM because the LOI is replenished.

You need to know the wet mass of the JPAP besides derived Dragon with ascent props and mission payload to surface.

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The math. It takes about 680 m/s to enter low lunar orbit. About the same for the TEI burn. So, 1360MS.

You only need to enter LLO. And, if Dragon was just used as a cargo vehicle to surface, it doesn't even need that, could do a direct landing. If the point was instrument/cargo on the Moon's surface at lowest delta v, one can use the mascons and the cancellation of angular momentum to land at even less delta v budget (very limited number of locations for this).

Now, for a mission planning POV, lets assume we choose an optimum LLO polar access orbit (10km periapsis, 200km apoapsis, longitude 32 degrees) - this is about as low as you'll go, and it will require deft care with small thrusters to maintain such for a month. You could eventually work up to a number of repeat sorties from a single Orion mission, perhaps as many as ten (this would be a logistical challenge requiring multiple "lunar CRS" vehicles/resupply, likely all of them, thus a mission worth doing not EM 1/2). It will cost more to enter this orbit then you've budgeted above - close to 800 m/s given optimal timing. Also, altitude will greatly vary, dropping to 8km and exceeding 200 km as the mascons retard/accelerate the combined SC, not to mention the dispersions either.

Each descent, hover, landing, ascent will require 5 km/sec delta v budget because the sites visited won't be as "easy" as the Apollo ones. So on orbit props will need to support 50 km/sec of props eventually for such a mission.

Which is why the big focus of this thread should be on propulsion and mass reduction. You can also see why you need such an incredible PMF to make a storable propellant single stage reusable lander to work.

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Round up for margins, 1500 m/s. ISP of a SuperDraco is about 240 at sea level. But, the fuel is MMH/NTO, which has a theoretical max of 336, so a superdraco with a vacuum expander bell (with electric actuators for steering) should do a lot better than 240. I'll ballpark it at 275, which I think is conservative.

What I would do is work backwards from the mass flow needed to get the thrust/iSP for the pumps/nozzle, and then you'd deal with the engine/tankage weight as part of the total vehicle's PMF.

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The dry mass of this upper stage should be, using a mass fraction of the S2 (again, I'm being conservative - this service module is just tankage and superdracos, and does not need to support Dragon and Trunk launch loads the way S2 does).

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Annnnd, ack, I can't find a mass figure, even a ballpark, for a superdraco. So, I'm going to totally ballpark it and take a SWAG, so basically my proposed service module for inside the trunk is a scaled down Stage 2 in mass fraction. S2 Dry mass (?) is 3900 kg. I'll scale that down, as the service module is a lot smaller, with fewer structural demands.

FWIW SuperDraco's are 3D printed which means they are very good on mass.

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Dragon2 plus internal SD fuel, etc, has reported mass of 7385kg. I'll add 1000kg for crew plus non-life-support consumables, putting it as 8385kg. That, plus dry service module (I've rounded that up to 1000kg - a very poor mass ratio compared to either F9 stages), 9385kg. So, per the rocket equation, we have a fuel mass for the service module (to get 1500 m/s delta/v) of 7000kg. That's about 1555 gallons. Even assuming the same density as water, it should therefor fit in a cylindrical unit within the trunk.

See above. You don't have delta-v budget to surface and back.

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So, the service module is a cylinder, 1000kg dry mass (It's far smaller than Stage 2, and I'm taking a wild guess as to SuperDraco mass), using 2 Dragon Superdraco engines. Here's where it finally gets relevant to this thread; It's also a baseline lander, derived in part from Dragon 2 components.

Without cargo, by itself, it has a delta/v of 5.5 kps, more than enough to land on the moon and take off again (you need 4.4 kps for that.)

How do you get these numbers?

One usually works from the mission architecture/profile and the desired orbit as a basis.

Then you need to determine LLO entry weight, descent weight at PDI, ascent weight at launch to LLO.

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It can carry 600kg of payload and still do the job (low lunar orbit, land, and come back). Crew accommodations would consist of lightweight aluminum tube Apollo style couches atop the cylinder (They're in space suits - no need for walls, life support, etc.).

Where do you get these numbers? An assumption?

None of these sound right.

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That same lander type, in one-way cargo mode, could land 2500 kg of cargo on the moon - for example a BEAM type module (With a dragon-based life support) for a short term hab, and other supplies. If added capacity is needed on the crew and cargo versions, it could be attained by stretching the tanks;

Nope.

BEAM is an experiment used to increase the TRL of an inflatable module. There is no "off the shelf" surface or orbital hab. Development of such is outside the scope of this thread.

Stretching tanks increases weight nonlinearly. And the assumption here is that you'd use a crasher JPAP with a lightened for ascent, replacement propulsion engines for SuperDraco's on vertical thrust structures (developing new engines alone would exceed the timeline here - SuperDraco's themselves haven't proven themselves, in fact has shortfall on pad abort- Bantam's for Starliner aren't any better).

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it could land and take off with one superdraco even with an additional couple of tons of fuel, due to the low lunar G. (The stretched version could thus include a stowed expandable hab on the crew lander).

Prove this assumption.

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A mission might look like this; a FH launches with a lander plus cargo and a crew lander, either stacked or side by side in a shroud.

Only in a fairing/shroud and on a PAF. The aerostructure is your primary weight reduction target.

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These go to low lunar orbit.

You need an LOI burn.

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A third launch is a fuel depot - not technically hard, as the fuel is storeable hypergolic.

Another vehicle to be developed. How does the fuel get to the vehicle. Where is the crew when the vehicle is fueled?

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4th launch, crew Dragon plus service module.

So no Orion as this thread is written? Does your crew Dragon have all of Orion's capabilities? Can it handle contingencies needed? What if the lander has a shortfall in performance and cannot reach crew vehicle?

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Rendezvous in lunar orbit. Crew handles docking plus topping up the two stages.

What if crew can't transit vehicles? What happens if theres a fueling mishap?

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Cargo lander lands the cargo - if successful, a crew descends on the crew lander, stays a few days, then ascends to rejoin Dragon for a return to Earth.

Is this the fuel vehicle or another?

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Crew lander remains in low lunar orbit, to be refueled from the depot for the next mission. This architecture is flexible; could be used to set up a base, or have a standby emergency ascent vehicle.

Is this a bit far fetched, and relying on a lot of assumptions and guesses? Yup.

Agree.

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I tried to be conservative, but I'm sure I missed some big things. I tried to keep it as cheap as possible, to make it viable for tourism. As part of this, I tried to keep it efficient (such as just couches on the lander, no structure or shell, and no staging, plus possibly reusable.)

To be fair you handwaived.

Sure - try taking the feedback and do some more homework.

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A few huge technical challenges/issues; Can a FH push 16385kg (Dragon plus service module) through TLI? If they can, as claimed, throw 10 tons at mars, maybe, but my guess is probably not. If they do stretch the second stage, then I'd feel better about it being plausible.

Another hard point is Lunar orbital rendezvous; hard to do. Can't use the GPS based system they use for ISS; GPS won't work in lunar orbit.

This part bothers me least.

Many ways to handle this. GPS works poorly in lunar orbit due to geometry (all the sats are all in the same location of the sky, you'd need a couple "orthogonal" to these) and range (delay, noise, and signal strength). One can also do active uplink of positional measurements from precision ground radars)

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The DragonEye laser docking system would - but navigation to close proximity will probably require either crew or a lot of work on the automated navigation system. Further problem, the fuel depot; storable fuel has been transferred in orbit before (such as to ISS) but I have no idea how hard it would be to accomplish for this.

Read my post upthread.

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I'm sure there are major flaws I didn't see - and I'd appreciate criticism and correction.

Hope you make careful use of it.

Many times one gives little here, because no one makes good use of the feedback.

You want more critical feedback, you do the "homework", show your work, and you'll get more involvement.

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...

But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...

But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.

Agreed for a reusable lander. I just didn't see the value of the additional complexity on a single use short stay along the lines of a Golden Spike proposal...

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...

But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.

Agreed for a reusable lander. I just didn't see the value of the additional complexity on a single use short stay along the lines of a Golden Spike proposal...

Ghost said extra points for a reusable lander so why not go for that?

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Chuck - DIRECT co-founderI started my career on the Saturn-V F-1A engine

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...

But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.

Agreed for a reusable lander. I just didn't see the value of the additional complexity on a single use short stay along the lines of a Golden Spike proposal...

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

Because you are flying under a fairing, these are quite possible (you'll at least need a minimal cover to reduce exposure in transit).

Also, one of the troubles with Dragon as a lander is that the side hatch is insufficient in size for suited access. This would deal with that.

Since these suits would be exposed to space for prolonged periods a simple MMD collapsible cover would be useful...

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

Because you are flying under a fairing, these are quite possible (you'll at least need a minimal cover to reduce exposure in transit).

Also, one of the troubles with Dragon as a lander is that the side hatch is insufficient in size for suited access. This would deal with that.

I realise Red Dragon is off-topic for this thread, but can't help thinking that if you're right, then from the 'artist concepts' we've seen they're going to have the same problems using a Dragon 2 variant on Mars.

Maybe mars-dust is better, but from what I've read, moon-dust is really nasty stuff and ingress into the cabin a non-trivial issue.

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With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they aregoing to land, and it could be dangerous sitting under them as they fly overhead.

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

Because you are flying under a fairing, these are quite possible (you'll at least need a minimal cover to reduce exposure in transit).

Also, one of the troubles with Dragon as a lander is that the side hatch is insufficient in size for suited access. This would deal with that.

Actually the Apollo LEM hatch was only 32" square.The Dragon hatch looks similar in size little more narrow but taller so a suited astronaut should fit esp since the door moves up and out of the way vs into the vehicle.Widening it slightly would be one of the easier modifications Dragon would need to land on the moon.Though I suspect they may have test fit a suit with backpack to arrive at the dimensions which BTW is how the LEM ended up with a square door in front.Originally the LEM was supposed to have a second docking port in front but it was a tight squeeze with the PLSS.

Dragon V2 has a NASA Docking System port on its roof. This allows the transferase of power and air. Can the water, fuel and LOX tanks be connected to the port? This would allow either refuelling or the attachment of drop tanks.

Dragon V2 has a NASA Docking System port on its roof. This allows the transferase of power and air. Can the water, fuel and LOX tanks be connected to the port? This would allow either refueling or the attachment of drop tanks.

There are provisions to allow for such transfers in International Docking System Standard (IDSS) Rev D release which were transferred from Mir's APAS-89 config to allow prop and oxidizer transfer via Progress, Soyuz, and the Buran system

The dragon would get to LEO + 1670 m/s, now that abort capability is no longer needed - separate from the second stage then burn the superdraco's to bring the dragon mass down to 5000kg and add a small amount more of delta V.

Launch a second FH with a payload of just an IDA (500kg) - no fairing or minimal nosecone. Rendezvous with the dragon and dock. At this point dragon is facing the second stage (rather than being mounted in the way it launched).

If docking fails then dragon can drop the trunk pallet and return home.

If docking succeeds then at this point the new second stage should still have 20,350kg of fuel, sufficient to push the lightened dragon (with its trunk fuel and engine) into TLI (3150 m/s above LEO).

Separate from the second second stage once translunar and the dragon has enough fuel for LOI, to meet the Orion etc then to land on the lunar surface. Later it can launch back to LLO then the dragon can TEI for a parachute landing (total 4560 m/s).

It appears to meet the requirements of the OP at the cost of two FH launches and requires no new technology. The dragon is returned to earth each mission, so learning and development can take place

Ive based all this on the figures I've been able to find for delta V budgets, weights and capacities etc - I'm happy to share the numbers.

The dragon would get to LEO + 1670 m/s, now that abort capability is no longer needed - separate from the second stage then burn the superdraco's to bring the dragon mass down to 5000kg and add a small amount more of delta V.

Launch a second FH with a payload of just an IDA (500kg) - no fairing or minimal nosecone. Rendezvous with the dragon and dock. At this point dragon is facing the second stage (rather than being mounted in the way it launched).

If docking fails then dragon can drop the trunk pallet and return home.

If docking succeeds then at this point the new second stage should still have 20,350kg of fuel, sufficient to push the lightened dragon (with its trunk fuel and engine) into TLI (3150 m/s above LEO).

Separate from the second second stage once translunar and the dragon has enough fuel for LOI, to meet the Orion etc then to land on the lunar surface. Later it can launch back to LLO then the dragon can TEI for a parachute landing (total 4560 m/s).

It appears to meet the requirements of the OP at the cost of two FH launches and requires no new technology. The dragon is returned to earth each mission, so learning and development can take place

Ive based all this on the figures I've been able to find for delta V budgets, weights and capacities etc - I'm happy to share the numbers.

Lunar escape is 2380 m/s, so an absolutely minimal budget for TLI>surface>TEI is twice that: 4670 m/s. So you lander Dragon can't get back to TEI, although it does look like it can make it to the surface and back to LLO

I think to fully close the mass budgets here you need a 3rd FH launch, which launches a crew Dragon with a similar trunk pallet (with less fuel) and vac engine directly to TLI. The crew rides the crew Dragon to LLO, then transfers to the lander Dragon for the the ride to the surface and back to LLO. This eliminates the need for the lander Dragon to have SuperDracos or parachutes or a heatshield, saving ~1000 kg, and it can be discarded on return to LLO.

Which engine are you proposing? SuperDraco fully expanded would get 340 - 345 sec I_sp at 90 kN, but will not hit your mass budget since it needs heavy tanks that can be pressurized to 1000 psi. You probably need a pump-fed engine like Aestus 2/RS-72, which gets 340 sec I_sp at 60 kN.

So asking for some help. I cannot locate any good numbers for the Dragon Pressure Vessel. Since my concept is based on using the pressure vessel sans all the exterior stuff I need the PV mass in order to calculate the mass ratio to compute the propellant requirements. Anyone have a source, or the actual (close) numbers?

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Chuck - DIRECT co-founderI started my career on the Saturn-V F-1A engine

I think to fully close the mass budgets here you need a 3rd FH launch, which launches a crew Dragon with a similar trunk pallet (with less fuel) and vac engine directly to TLI. The crew rides the crew Dragon to LLO, then transfers to the lander Dragon for the the ride to the surface and back to LLO. This eliminates the need for the lander Dragon to have SuperDracos or parachutes or a heatshield, saving ~1000 kg, and it can be discarded on return to LLO.

The original presumed architecture here was Orion/SLS for crew, and single launch under fairing with PAF of CC derived, dedicated lander to LLO. SLS in this case has considerable excess capacity, so it could also "carry the lunch" e.g. props for a lander (reuse). To replace Orion/SLS, likely one either needs more or a different architecture to add in capacity. Which could be as little as a F9US lofted by a F9R, assuming you have a means to use that capacity creatively ...

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Which engine are you proposing? SuperDraco fully expanded would get 340 - 345 sec I_sp at 90 kN, but will not hit your mass budget since it needs heavy tanks that can be pressurized to 1000 psi. You probably need a pump-fed engine like Aestus 2/RS-72, which gets 340 sec I_sp at 60 kN.

IMHO the three biggest issues for Dragon 2 NOT being ideal as a lunar lander are a) underexpansion, b) lack of a pump driven engine, and c) tank weight due to increased volume of props needed. For a reusable lander, this issues become critical.

There is no way one gets a rapidly developed lander here except with off the shelf engines, either integrated in pallet, or ... using the feeds/mounts for the SuperDracos but from different, larger tankage (certain issues here).

Getting to 340 iSP on a hypergolic engine is not easy. Also, the nozzle rides the vehicle CG up high.

Also, any non SLS lunar exploration mission architecture ... only becomes economic with a reusable lander at a minimum.

PS. Watch out - Musk convince Amber Heard to go on another of their "weird dates" once again. Usually coincides with something unexpected coming out of SX ... ... actors are good at "pretend" ...

I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.

Thinking about this a bit more... Leave the standard hatch as is and on the opposite side cut out an opening and weld in a flange for the "suit-port airlock"...

I may be pushing the boundaries of Dragon or Starliner-derived lander here - so, SpaceGhost, if you feel I have, let me know and I'll delete my post.

It's a fine post. On topic and relevant. I'll attempt to give you feedback.

Thank you!

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Operating premise; keep costs down, including R&D. Use existing tech (Dragon2, in this case) as much as possible. That means, in part, keep it as simple as possible. It also means avoiding unneeded mass. It would require lunar orbit rendezvous like Apollo.

Correct. And the existing tech also includes associated mission systems. Since docking is standardized, other vehicles that may be used like Orion have systems as well, but outside of such standardized interfaces, you don't "mix and match".

You do LOR because of the limitations of the combined systems. Each has a means to arrive on LLO. Adding complexity to share the ride slows things down. And you can use the excess performance margin for extended capabilities later. But it introduces risk, contingencies, and variables. Likely you want the CC derived lander on LLO ahead of crew launch, and thus it must last significantly longer.

The need for in-space duration is why I stuck with hypergolics, in spite of the awful ISP. A cryo-fueled lander would, IMHO, be a monumental development project, which huge mission duration issues. The docking issue... I'm thinking a simple-as-possible drogue and shroud capture system (Perhaps modeled on Gemini-Agena), because the crew lander doesn't have a hatch or an airlock (there's no crew cabin on the crew lander)Rather pointless without a crew cabin on the lander). I went with crew-piloted docking because I did not know if the autodocking systems used for ISS docking could work in low lunar orbit. I guessed they could, but wasn't sure. I'd much prefer automated rendezvous/docking.

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Wouldn't call it a SM. Dragon has an integral SM.

Would call it a jettison-able propulsion assist pallet (JPAP). Use the Dragon's trunk/radiator/other systems to keep PMF low, might construct CF tanks with integral thrust structure and membranes to get below F9US PMF.

Good point; it's a jettison-able propulsion assist pallet. I need it to fit within the trunk, not be part of the trunk, due to abort requirements. I used it as the basis of a lander for cost reasons - comonality.

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Essentially, a cylinder, slightly smaller in diameter than the F9 (to fit within the Dragon trunk), containing Superdracos (2, for redundancy) and fuel. Theoretically, you should be able to make this with about the same mass ratio as the upper stage. It'll be a short cylinder, mounted behind the trunk, size dictated by needed delta/v and thus tankage capacity.

Not how you do it.

You calculate your mission's needs, including contingencies venting etc, the length of engines/nozzles/gimbal freedom/recontact margin/jettison compliance/other. From these you get the overall tanks/pallet dimensions, size the trunk from that. Not the other way round. Oh, and I forgot, you need to add mission growth margin.

Then you can call it short, medium or long.

Sorry, but while I agree in general, I disagree in this particular instance. For this concept of mine to be even remotely plausible, the JPAP has to fit within the trunk - not be part of the trunk, and the trunk can't be redesigned (far too costly). If it won't fit, my concept is kaput - so I looked at making it fit first, as it's an instant deal-killer if it does not. The good news IMHO is the Dragon 2 trunk looks like it has ample volume (though that's a SWAG on my part - I can't find figures to support it - yet).

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The math. It takes about 680 m/s to enter low lunar orbit. About the same for the TEI burn. So, 1360MS.

You only need to enter LLO. And, if Dragon was just used as a cargo vehicle to surface, it doesn't even need that, could do a direct landing. If the point was instrument/cargo on the Moon's surface at lowest delta v, one can use the mascons and the cancellation of angular momentum to land at even less delta v budget (very limited number of locations for this).

Now, for a mission planning POV, lets assume we choose an optimum LLO polar access orbit (10km periapsis, 200km apoapsis, longitude 32 degrees) - this is about as low as you'll go, and it will require deft care with small thrusters to maintain such for a month. You could eventually work up to a number of repeat sorties from a single Orion mission, perhaps as many as ten (this would be a logistical challenge requiring multiple "lunar CRS" vehicles/resupply, likely all of them, thus a mission worth doing not EM 1/2). It will cost more to enter this orbit then you've budgeted above - close to 800 m/s given optimal timing. Also, altitude will greatly vary, dropping to 8km and exceeding 200 km as the mascons retard/accelerate the combined SC, not to mention the dispersions either.

Each descent, hover, landing, ascent will require 5 km/sec delta v budget because the sites visited won't be as "easy" as the Apollo ones. So on orbit props will need to support 50 km/sec of props eventually for such a mission.

First, thanks for the LM delta/v specs and the 5kps spec. I could not find those. That's a higher delta/v from LLO to the surface than I thought - and pretty much blows my concept of a single stage return crew lander with a 1000kg dry mass or superdracos.

The entering/leaving LLO was for the Dragon2, not the landers. Bad wording on my part.

Given the delta/v requirements from LLO to the surface and back, it does not make economic sense to me to push mass that's not needed on the surface through 5 kps. Heat shield, structure, etc. What's really needed, IMHO, is to leave as much as possible on the lunar surface - sent by a one-way lander. What needs to come back up to LLO is, really, crew and space suits. No need for a crew cabin, etc. However, suits can fail (leaks, etc) prior to ascent, so a backup would be required. I was thinking of the shuttle "Rescue ball", which went as far as a prototype. Or, a spare spacesuit.

Hrmmm.. However... if 5 kps is what's needed from LLO to the surface and back, and the lander had a mass fraction close to that of the F9 second stage... it's still doable, but marginal. Depends on ISP. I'll get to that later in this post. A further issue; approaching the mass fraction of the F9 S2 is probably implausible for any stage using pressure-fed engines, because the tankage will be a lot heavier if it has to withstand pressurization. Perhaps the F1 upper stage (Kestral was pressure fed) would be a better guide as to a plausible mass fraction?

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Round up for margins, 1500 m/s. ISP of a SuperDraco is about 240 at sea level. But, the fuel is MMH/NTO, which has a theoretical max of 336, so a superdraco with a vacuum expander bell (with electric actuators for steering) should do a lot better than 240. I'll ballpark it at 275, which I think is conservative.

What I would do is work backwards from the mass flow needed to get the thrust/iSP for the pumps/nozzle, and then you'd deal with the engine/tankage weight as part of the total vehicle's PMF.

I love the AJ-10. It's got a long history, very reliable, and great ISP for a storable. It also has available specs, including mass. I went with Superdraco, originally, because I assumed it's cheaper, but I flat out don't know (nor was I able to find out the price of either). I also wanted redundancy if practical. I was also trying to stay within the Dragon/Starliner derived rules, so I tried to use Dragon components. The AJ-10 DeltaII upper stage would actually have made a near ideal JPAP, almost off the shelf, because it's low dry mass (950kg), higher ISP, and *might* fit inside a Dragon 2 trunk (the stage is 2.6 meters diameter, 6 meters long) as well as being the basis for a lander - but it's not a Dragon or Starliner component, so I didn't try that route.

However, because the AJ-10 has a great ISP, plus has things like a known mass, I'll use that for now - if you're okay with that on this thread.. However, due to size constraints plus reuse potential, I'd prefer the Shuttle OMS version (with its smaller, non-ablative, engine bell) in spite of its lower ISP of 316.

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Dragon2 plus internal SD fuel, etc, has reported mass of 7385kg. I'll add 1000kg for crew plus non-life-support consumables, putting it as 8385kg. That, plus dry service module (I've rounded that up to 1000kg - a very poor mass ratio compared to either F9 stages), 9385kg. So, per the rocket equation, we have a fuel mass for the service module (to get 1500 m/s delta/v) of 7000kg. That's about 1555 gallons. Even assuming the same density as water, it should therefor fit in a cylindrical unit within the trunk.

See above. You don't have delta-v budget to surface and back.

That's because the Dragon 2 does not go to the surface. It stays in LLO. Only the landers actually land.

Not viable for my concept; you'd be pushing a lot of superfluous mass through 5kps if you try to land a Dragon on the moon and take off again. Very prop-rich architecture, and needing a large dedicated landing stage and ascent stage. I'm trying for something lower-cost.

A lander using Dragon components (SuperDraco, avionics, dracos) that's largely the same as the jettison-able propulsion assist pallet I outlined. It's a squat cylinder. Add legs, and Dracos for maneuvering. On the flat upper surface, put four light collapsible canvas (or similar) seats, and a deployable control console, (could be cable-connected, strapped to a crewmember's lap). No cabin, just seats. They'll meet up with supplies/inflatable hab on the surface. This gets rid of a heck of a lot of mass and engineering cost.

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Without cargo, by itself, it has a delta/v of 5.5 kps, more than enough to land on the moon and take off again (you need 4.4 kps for that.)

How do you get these numbers?

One usually works from the mission architecture/profile and the desired orbit as a basis.

Then you need to determine LLO entry weight, descent weight at PDI, ascent weight at launch to LLO.

I got the delta/v for LLO to lunar surface from looking up several delta/v maps. Apparently, that's a bad method, because your numbers (including for the LEM) are considerably higher. I'll use yours.

I assumed a dry mass of 1000kg for the lander - which is nothing more than a cylinder (containing fuel tanks) and (originally) two superdracos. I'll go with a single AJ-10 instead. Still 1000kg dry mass (Which I think is a poor mass ratio and could be reduced a little... though not a lot.). The mass of the crew plus spacesuits: I'm guessing 200kg per person (person plus spacesuit) based on the following: the Apollo suits weighed around 81kg including backpack. I have no idea what a modern space suit (Such as SpaceX and Boeing are working on), modified as a lunar EVA suit, would weigh, so I'm wild-guessing (with, yes, plenty of handwaving) 100kg. I'm guessing the same for the occupant, so 200kg per crew, 800kg if we're landing 4. The only remaining mass is the seats plus small control console... the latter would be akin to a laptop in mass - call it 5kg. The seats? 5kg each?. So, payload plus dry mass, 1825 kg. ISP 316 (Shuttle AJ10). Delta/v potential, 4883.9 m/s, not enough.

However, if the lander could achieve a better mass fraction, closer to the F9 1st stage, , to get the dry mass down to 600kg, delta/v goes up to 5506 m/s with the same 825kg payload. Enough for a round trip from LLO to the surface and back, with higher-than-speced margins. Or, more plausibly, reduce the number of crew by one.

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That same lander type, in one-way cargo mode, could land 2500 kg of cargo on the moon - for example a BEAM type module (With a dragon-based life support) for a short term hab, and other supplies. If added capacity is needed on the crew and cargo versions, it could be attained by stretching the tanks;

Nope.

BEAM is an experiment used to increase the TRL of an inflatable module. There is no "off the shelf" surface or orbital hab. Development of such is outside the scope of this thread.

Okay. Hrmmm. My concept needs a hab of some sort on the surface (Due to no crew cabin on either lander). So... existing hardware (well, almost existing); A Dragon 2 - perhaps used. Strip it of superfluous mass (Heat shield, parachutes, seats). Put the proposed JPAP (or a a Delta II AJ-10 upper stage) in the trunk (if it'll fit - if not, won't work) and launch it on course for a direct-decent to the lunar surface - with as close to zero velocity at the earth-moon gravity threshold as possible (Though I suspect Apollo is a good guide for that, even though heading for LLO). For landing, drop the trunk, burn the JPAP dry, then drop the JPAP. Use Dragon's SuperDracos to land. Okay, the math; delta/v needed for this, bare minimum, is (if my delta/v maps are accurate) about 2.5 KPS to land with no margins at all. So, call it 2.6 (It's unmanned, so margins aren't as important). That JPAP had the ability to push Dragon and trunk through 1.4 kps. Dragon 2's internal delta/v capacity was calculated to be (sans trunk) 742 M/S doing a hoverslam-mode landing in vacuum. I didn't do the calc, but the person who did looks to have done a good job, his work is here; https://www.reddit.com/r/spacex/comments/4qwpdz/dragon_2_landing_calculations_analysis_for/

1.4 + .742 is 2.142 kps. Not enough, but that's without factoring for dropping the trunk or increasing the fuel capacity of the JPAP. Seeing as I can't find the mass of the trunk, I have no clue how to go further... but *IF* this would work, there's the Dragon-derived surface hab. (It'd need solar cells, due to not having a trunk on the surface). And if that's the route, we can dispense with the one-way (LLO to surface) cargo version of the JPAP based crew lander.

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it could land and take off with one superdraco even with an additional couple of tons of fuel, due to the low lunar G. (The stretched version could thus include a stowed expandable hab on the crew lander).

Prove this assumption.

If you mean prove that a stretched version could land a stowed expandable hab along with crew, I can't because I was wrong. It'd need to be a very light hab, 1000kg or so, plus there's nowhere safe to put it (the crew would need to sit on top of it...). Not plausible.

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These go to low lunar orbit.

You need an LOI burn.

That has to be provided by the landers, which is unfortunately why this concept needs a fuel depot in LLO. The latter, though, has the benefit of making the crew lander reusable.

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A third launch is a fuel depot - not technically hard, as the fuel is storeable hypergolic.

Another vehicle to be developed. How does the fuel get to the vehicle. Where is the crew when the vehicle is fueled?

I don't like the need for the depot, but I couldn't see a way around it. For the fuel transfer, I was thinking something similar to the system the Progress tankers use to refuel ISS's propulsion module. Simple connectors within the docking mechanism (If what I've read is correct). In my proposal, there's no atmosphere-containing passage as part of the docking mechanism, so less risk and complexity (should be easier - theoretically.).

As for where the crew would be during lunar orbit refueling of the lander... my preference is doing their last few days of launch prep at the Cape. No point in launching them unless the landers are refueled, and the cargo one has landed their supplies and accommodations on the moon.

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4th launch, crew Dragon plus service module.

So no Orion as this thread is written? Does your crew Dragon have all of Orion's capabilities? Can it handle contingencies needed? What if the lander has a shortfall in performance and cannot reach crew vehicle?

No Orion; Dragon 2 with the JPAP serves that role (Same as the Apollo CSM stack). Your OP post isn't written so as to require Orion. It said, "meant to dock with say Block 1/1B SLS launched Orion?" I read the "say" and question mark as indicative of suggestion, not specification.

The Dragon 2, with the jettison-able propulsion assist pallet, should have the delta/v margin to handle a lander takeoff shortfall - assuming the lander actually makes orbit. Does Dragon have all of Orion's capabilities? No. But does it have (with the JPAP) enough? I think so (but I may well be wrong).

In any case, I couldn't see a way to make Orion part of this (Even if we overlook the huge cost) because I couldn't see a way, off-the-shelf, to get Orion and its SM through TLI that does not involve the letters "SLS" and it's even more astronomical cost (and thus implausible for my concept.) A further issue: slow launch cadence.

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Rendezvous in lunar orbit. Crew handles docking plus topping up the two stages.

What if crew can't transit vehicles? What happens if theres a fueling mishap?

If you're right that the docking can be automated, then the crew will be safely on Earth during lunar orbit refueling of the landers. They'd launch after that, assuming all went well. If the crew can't, for some reason, transfer from the dragon to the crew lander (which is a simple EVA of leaning out the open Dragon hatch, clipping a tether to the lander, climbing into the seats, and buckling in) then mission aborted, and back to Earth they go. If, on the other hand, they can't get off the lander and into the Dragon, it's a very bad day - but wouldn't that be the case with any lander that isn't also the return vehicle?

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Cargo lander lands the cargo - if successful, a crew descends on the crew lander, stays a few days, then ascends to rejoin Dragon for a return to Earth.

Is this the fuel vehicle or another?

The fuel depot remains in lunar orbit, it does not land (it can't). It's just there to top up the cargo lander and the crew lander/ascent. However, now that you mention it... it'd be nice if there was also the ability to top up (in case of emergency need) the Dragon's jettison-able propulsion assist pallet.

I don't like the need for a fuel depot. Its complexity and cost makes this even harder. But, refueling is needed to make reuse possible - and also due to the need to get the landers into LLO on their own power.

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Crew lander remains in low lunar orbit, to be refueled from the depot for the next mission. This architecture is flexible; could be used to set up a base, or have a standby emergency ascent vehicle.

If you're right that autonomous docking is feasible, then autonomous docking, and autonomous landing . However, pilot override ability during landing would be a must IMHO for the manned lander.

Lifetime? I have no idea how to begin to calculate that. Other consumables replenishment - food, O2. water, lithium dioxide, etc... would have to come in the Dragon along with crew. (Perhaps I'm way overoptimistic saying a crew of 4... two would make this a lot easier).

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I tried to be conservative, but I'm sure I missed some big things. I tried to keep it as cheap as possible, to make it viable for tourism. As part of this, I tried to keep it efficient (such as just couches on the lander, no structure or shell, and no staging, plus possibly reusable.)

To be fair you handwaived.

Sure - try taking the feedback and do some more homework.

I'm trying, but I'm so out of my depth that that in many cases I don't even know what I don't know.

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A few huge technical challenges/issues; Can a FH push 16385kg (Dragon plus service module) through TLI? If they can, as claimed, throw 10 tons at mars, maybe, but my guess is probably not. If they do stretch the second stage, then I'd feel better about it being plausible.

Unless FH (non-expendable mode) can push 16 tons (Dragon2 plus the jettison-able propulsion assist pallet) through TLI, I'm flat out sunk - the concept just isn't viable. Raptor US might make it possible, but that's ifs on top of ifs with a unicorn for a side booster at this point in time as far as my concept is concerned. IMHO, my first step should be figuring out what, exactly, FH can push through TLI. SpaceX's figures keep changing. In 2011, it 19 tons to GTO and 16 tons to TLI. In 2013, they upped that to 21.2 tons to GTO, but didn't mention TLI. Even if that's a commensurate increase, I don't think it's enough to allow FH to do the job in anything but expandable mode. And if so, that makes my concept preposterous in an of itself; it's only plausible costwise if FH is in recoverable mode. The reason is this architecture is going to take (once the pieces are in place) two FH launches per landing, and if one is expendable mode, that's 150 million right there - for just the one launch, not counting payloads.

HRMMM... maybe there is a way. Have the JPAP only partially fueled (enough to enter LLO and reach the fuel depot) for launch - but that'd mean the refueling of it would be both manned, and also life-or-death (no way home without it). And, without knowing what the FH can actually push through TLI in reusable mode, there's no way (That I can see) to figure out if this is even plausible from a mass perspective. (on the other hand, if FH can't do it, it's 100% implausible).

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I'm sure there are major flaws I didn't see - and I'd appreciate criticism and correction.

Hope you make careful use of it.

Many times one gives little here, because no one makes good use of the feedback.

You want more critical feedback, you do the "homework", show your work, and you'll get more involvement.

All I can say is I'll try. You've made me realize I have a vast amount of homework to do. Thank you for your help and feedback.

My take at the moment; my concept has too many flaws, and also too many unknowns. I'm also very dubious that it would fit this thread, due to switching from Superdraco to AJ-10 for the lander.

Yet another flaw just occurred to me; use of GPS for docking or, especially, landing, is problematic even if possible; you're going to have no GPS for around 40% of each orbit (Depending where periapis is) and it also places anything not on the earthside of the moon off limits (but the lack of a comms relay pretty much does that anyway).

A lot of good thoughts in the post above, and reasoned speculations. I think, though that the only way to get this to close is by a 2x launch (1.5 launch CXP) that sends an approximately 22 ton spacecraft up on an expendable Falcon 9 and an Earth Departure Stage (EDS) up on a Falcon Heavy expendable. Apollo needed more than 70 tons of LOX/LH2 to send about 50 tons on TLI. With the lower quantity and Isp of LOX/RP-1 on a Falcon upper stage - 22 tons to TLI sounds about right. I'm assuming that both Lunar vehicles are Dragon-derived.

Dragon 'Command Module' - Adapted Dragon 2 with Propulsion pallet in it's Trunk (an idea first touted by me; but based on a Golden Spike requirement)The Prop Pallet's delta-v is intended to be enough for LOI and other plane-change and circularization manuevers, and also Trans-Earth Injection later. Dragon CM also has a high-gain comms antenna. Target mass injected into LEO on an expendable Falcon 9 Block 5 is 20-to-22 tons.

Dragon 'Lunar Module' - Launch weight on Falcon 9 expendable; 22 tons is the goal. Adapted Dragon 2 with no heatshield or Earth recovery systems. Pressure shell is from Dragon 2, but is surrounded by MMOD shielding and insulation - matching the form factor of a standard Dragon outer 'cone' backshell, but a bit 'bulgier'. This is based on Chuck's Dragon LM suggestions. Trunk contains Propulsion Pallet that acts as a Powered Descent Initiation stage - this is ejected before the 'High Gate' point in 'crasher mode' and the Dragon Lander uses conformal propellant tanks to finish the descent. The Lander has a small detachable porch and ladder beyond the main hatch that has the Astronauts emerging from it for the first EVA. At the rear of the cabin - opposite side to the hatch and windows - is a dual suitport station. Before ending the EVA, the crew detach the ladder and porch and replace it to the rear where the suitports are. This is their ingress/egress point for the rest of the EVAs. Surface stay time for two Astronauts is to be 7 Earth days with 6 or 7 EVAs. A micrometeroid shield to protect the suits between EVAs could be roller-curtain assembly.

However: The main hatch on one side and the suitports on the opposite side might be too complex - a suitport to either side of the main hatch instead of the two windows might be a better place for them; with a shared porch and small ladder to the surface. The landing and ascent would be largely automatic - if the crew had to manually take over from a malfunctioning Autopilot, they could 'see' with a pair of ultra hi-def 3D TV screens.

Ascent could be from onboard propellant supplies in the 'bulged', conformal tanks. And in all the above details - this Dragon Lander concept is not meant to be reusable. But it could be, if we took Chuck's earlier idea in the thread a step further: the Cabin Stage could be mounted upon a new structure of leg/prop tank set each time - brought fresh from Earth by the Dragon or Orion Command Module. No need to physically plug and unplug the prop tanks alone each time - make the tanks and legs a single, integrated structure able to be mated to the previously used Cabin Stage again and again. This would be a little bit like using an Apollo Ascent Stage over and over, with a fresh Descent Stage each time. But make the connections and prop transfer lines for the Dragon Cabin Stage and Prop/Legs far easier than that idea that I just made a crude analogy of.

EDIT: I'd draw a sketch of what I meant above, but I don't currently own a working scanner.

« Last Edit: 03/03/2017 01:28 PM by MATTBLAK »

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I don't think operating from LLO is practical, may make lander design easier but neither Orion or Dragon can operate in LLO. The Orion is capable of entering and leaving higher orbits DRO and NRO. With right US or extra fuel, Dragon could use these orbits.

Q: would electric pump fed super-draco be considered feasible for purpose of this discussion?Reason: Electron rocket mass fraction is better than pressure fed stages of similar prop loads (delta II US, Araine 5G US). In that case significant time and cost in development was saved by using electric pump fed over combustion cycle based pumps. I think the same case could be made for dragon derived lunar lander, fluid handling would be greatly simplified without transfer of pressurizing gases.

Q: would electric pump fed super-draco be considered feasible for purpose of this discussion?Reason: Electron rocket mass fraction is better than pressure fed stages of similar prop loads (delta II US, Araine 5G US). In that case significant time and cost in development was saved by using electric pump fed over combustion cycle based pumps. I think the same case could be made for dragon derived lunar lander, fluid handling would be greatly simplified without transfer of pressurizing gases.

Q: would electric pump fed super-draco be considered feasible for purpose of this discussion?Reason: Electron rocket mass fraction is better than pressure fed stages of similar prop loads (delta II US, Araine 5G US). In that case significant time and cost in development was saved by using electric pump fed over combustion cycle based pumps. I think the same case could be made for dragon derived lunar lander, fluid handling would be greatly simplified without transfer of pressurizing gases.

Focus is on rapid development of CC-derived lander or optional reusable one (stretch goal for gifted engineers).

Please also be critical on me if you see something wrong/missing. Still working on clongton's needs for Dragon 2 PV.

When launching from the Earth solar panels have to be retracted to reduce air resistance, being in a vacuum lunar surface and spacestation launches do not have this problem. However the skeleton of the solar panels will have to take the accelerations of take-off and landing.

When I think of weight reduction of spacecraft for some reason I remember Sojourner's rocker arms and how they drilled all those holes to reduce weight. Could something similar be done on the pressure vessel or would the material to enclose the cab add just as much weight?

Could you please explain more about the ladder? I don't follow why you need to move the ladder which should only be needed under the suit location...

At the time I was writing and thinking this through, that I didn't want the suits to be launched and ride to the Moon, and then down to the surface on the outside of a Suit Lock. Though, of course this is entirely possible that they could, if they were protected by the payload shroud at launch and a MMOD shield the rest of the time. I thought that the crew could be wearing their clean suits within the Lunar Module during descent and landing; as the Apollo Astronauts did. But then the idea was to leave their dirty selves outside the Lander hatch after the first EVA; but I reasoned that they might need Suit Locks separate from the front, up-swinging Dragon hatch if that were so - hence my slightly clumsy idea of putting the Suit Locks around the back.

I realize now - in the spirit of brainstorming at 2:30am (when I wrote it) that that was probably a weak idea. I think the best way to ensure inclusion of the Suit Lock idea is to make the main Dragon Hatch also a Suit Lock after the first EVA, where both Astronauts emerge from that hatch one by one, the first time. But also have a pure Suit lock station built into the hull alongside that hatch - just widen the porch a little so both Astros can back into their suit ports at the end of the EVA. A glorified 'roller blind' MMOD and thermal shield could be raised and lowered as needed over the suits between EVAs.

Also: in using the Dragon 2 pressure shell idea; without the heavy, conic 'backshell' - taking a leaf out of the Apollo LM's book; that shell could be surrounded by thermal and MMOD shielding - covering propellant and helium tanks and radiators and other necessary plumbing. I imagine that a 'naked' Dragon pressure shell would look plenty odd with all the added protruding bumps and bulges then covered with gold mylar foil - but I'd love a talented scratch-building modeller to have a crack at building our Dragon Lunar Module!

« Last Edit: 03/03/2017 10:33 PM by MATTBLAK »

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...Or just make the main front hatch large enough to be a one hatch/2 suit port combo arrangement...

Found a picture of the Dragon 2 Pressure Shell - add Chuck's legs and prop tanks, radiators and plumbing at the rear of the shell and my Hatch/Suitports/Porch & Ladder at the front. Also, for surface stay time; the onboard batteries could be augmented by a small, single solar array - or the craft could have all 'spare' surface area covered by solar cells.

Could you please explain more about the ladder? I don't follow why you need to move the ladder which should only be needed under the suit location...

At the time I was writing and thinking this through, that I didn't want the suits to be launched and ride to the Moon, and then down to the surface on the outside of a Suit Lock. Though, off course this is entirely possible that they could, if they were protected by the payload shroud at launch and a MMOD shield the rest of the time. I thought that the crew could be wearing their clean suits within the Lunar Module during descent and landing; as the Apollo Astronauts did. But then the idea was to leave their dirty selves outside the Lander hatch after the first EVA; but I reasoned that they might need Suit Locks separate from the front, up-swinging Dragon hatch if that were so - hence my slightly clumsy idea of putting the Suit Locks around the back.

I realize now - in the spirit of brainstorming at 2:30am (when I wrote it) that that was probably a weak idea. I think the best way to ensure inclusion of the Suit Lock idea is to make the main Dragon Hatch also a Suit Lock after the first EVA, where both Astronauts emerge from that hatch one by one, the first time. But also have a pure Suit lock station built into the hull alongside that hatch - just widen the porch a little so both Astros can back into their suit ports at the end of the EVA. A glorified 'roller blind' MMOD and thermal shield could be raised and lowered as needed over the suits between EVAs.

Also: in using the Dragon 2 pressure shell idea; without the heavy, conic 'backshell' - taking a leaf out of the Apollo LM's book; that shell could be surrounded by thermal and MMOD shielding - covering propellant and helium tanks and radiators and other necessary plumbing. I imagine that a 'naked' Dragon pressure shell would look plenty odd with all the added protruding bumps and bulges then covered with gold mylar foil - but I'd love a talented scratch-building modeller to have a crack at building our Dragon Lunar Module!

Thanks for the reply. No worries I come on here often on many a sleepless night and post, that's why there is an edit button for the next morning! Don't take my original lander from 5 years back too literally since that was the first variant of the crew Dragon at the time and not the current one. One of my inspirations came from the Phoenix lander but we could lose the aero-shell of course. Back then we had similar pressure vessel to what we have been discussing with Chuck, I just can't find the thread as it had some sketches as well on it...

I love the LUNOX horizontal lander design! It reminds me of the dear old, Sci-Fi Space: 1999 Eagle. A craft like the above should be able to fit in a 5.2 meter or similar payload fairing. It could encourage reusability if storable propellants are used and the configuration was easily refuelable with a tanker module sent either robotically or brought each time by the Command Module. Lunar ISRU is quite a way off, sadly but a later 'Block' version of this could be upgraded to cryogenic propellants made in part or fully from Lunar water. I could see a craft like this as a better use for the Starliner as the front, conic Command Module analog portrayed in the picture - though I suspect that the one in the picture is a smaller diameter than the Starliner.

And on the Lunar surface, the 'wall' of the Command Module's cone would become the 'floor' - that might make an interesting shape to stand and maneuver around in. Though, for the purpose of this thread's design aesthetic, we are assuming a vertical landing configuration of Dragon or Starliner.

In fact, here's a link to the old ESAS Lunar Architecture document - from page 124 onwards there are interesting diagrams for a using a Starliner-shaped capsule in the Lunar Lander design and the resulting crew layout:

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.

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The drawings are from the ESAS document that Mattblak had identified. The idea of using a capsule as dual-use is interesting. An expandable port module mounted below the capsule between lander legs is interesting.

Here's a derivative of that craft that I drew more carefully for a science fiction novel I was researching about 20 years ago. I didn't write that story - but I may still yet The story idea is sort of an update of an idea 'borrowed' from Martin Caidin's 'Marooned'.

Here's a derivative of that craft that I drew more carefully for a science fiction novel I was researching about 20 years ago. I didn't write that story - but I may still yet The story idea is sort of an update of an idea 'borrowed' from Martin Caidin's 'Marooned'.

You have to write it! I like the drawing, ideally we would like to keep the ladder as short as possible in any design whether horizontal or vertical in design...

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.

I really like the suit ports too, but since they are basically airlocks in of themselves I'm assuming they are heavy. IMO the best lander would be built around the SEV cab if it's abilities are to be believed, but the other's might leave room for growth beyond a two person crew.

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.

I really like the suit ports too, but since they are basically airlocks in of themselves I'm assuming they are heavy. IMO the best lander would be built around the SEV cab if it's abilities are to be believed, but the other's might leave room for growth beyond a two person crew.

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

Suit ports are the optimal solution for moon dust. Pairing with a suboptimal solution for a lander just doesn't seem right to me. I see a suboptimal solution like a collapsible mud room with a vacuum hose and filtration system for the dust as a better fit. We already know the dust won't kill you so going with experimental and cheap shouldn't be an issue.

Do the research on the suit ports, find the weight. Since the vehicle will fly under a fairing, you don't have to stow/clean/enter/exit the suits, which also takes weight - so it's not all added weight.

The suit ports also mean you have more surface time. And, if the suits are lower to the surface, less weight/trouble to to EVA, operations can be automated to prepair/consumables/integrity check.

You could also have shorter, multiple sorties or hops. If you were planning surface ops following stratigraphy, layout of a base perimeter/line runs, or charting/sampling lunar ice in crater shadows, you could cover a lot of ground in a short space of time that way.

So for a refuelable, reusable, multi-sortie mission design ... you might be able to gather enough "results" in a single month LLO mission, that your next mission in 6-12 months might be able to deploy to the same locations visited, instruments/mining equipment/base components. Or have independently flown cargo landed at those sites in the intervening time.

A powerful mission architecture built out of existing developed componentry.

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

Suit ports are the optimal solution for moon dust. Pairing with a suboptimal solution for a lander just doesn't seem right to me. I see a suboptimal solution like a collapsible mud room with a vacuum hose and filtration system for the dust as a better fit. We already know the dust won't kill you so going with experimental and cheap shouldn't be an issue.

Do the research on the suit ports, find the weight. Since the vehicle will fly under a fairing, you don't have to stow/clean/enter/exit the suits, which also takes weight - so it's not all added weight.

So the only available suits are outside of the spacecraft and only available through the suit ports. I didn't know the technology was that far along for that to be acceptable, but I'm glad it is.

Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.

Next step is to find the weight of everything the suit port would displace. So, find the suit weights, and all of the suit related equipment/brackets/lockers/replenishment/hoses/volume/etc. Hint: you can find in Orion/Apollo manifests some of this, and SWAG the rest.

So you create a total weight/cost/volume/... of w/ and w/o suit ports. Now you know the trade. My bet is that the suit lock will be slightly better due to tighter integration having less mass growth. Also, realize that the suit lock is a true airlock, unlike LM/CSM evacuating/re-pressurizing entire volume - which means cost of replenishment is part of the trade ...

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

You might be surprised by how much the totals are here.

I'm surprised that you would do 10-20 sorties in a max 4 day mission with only a expendable Dragon or Starliner derived lander.

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

You might be surprised by how much the totals are here.

I'm surprised that you would do 10-20 sorties in a max 4 day mission with only a expendable Dragon or Starliner derived lander.

Upthread is described a reference orbit with a maximum mission (month LLO). This would be a topmost goal for a reusable lander. The point is to be able to rank missions/architectures/vehicles/devtime/... against each other, by figure of merit.

By necessity of the CC derived base, whose abort capability represents a base propulsion for orbital ascent, one chooses a reference orbit that can a) be achieved/maintained, b) puts the burden on the earth transit crew vehicle, and c) allows the largest number of surface access opportunities to visit.

This allows an expendable, minimal mission (likely few days) to be flown with margin/contingencies. If it is flown, follow-on reflights w/option for reuse, incrementally uprated to the maximum suggested, represent a compelling goal that far exceeds Apollo program. Perhaps a reason to be considered, and worth the effort?

And it lets others decide what the surface objective(s) might be? The same architecture could build a base, prospect/mine/produce/launch propellant/ISRU/other, learn the story of lunar formation/processes/resource/access, ...

An excuse to get serious. Back on topic of "Dragon 2 or Starliner derived dedicated lunar lander?".Propulsion? Mass? Concept? Trades?

Would the cabin be an Earth reentry capsule or a simpler structure?The life support (ECLSS) and control systems could be the same ones used in a CST-100 or Dragon V2 and put in say a square box. The appropriate sized fuel tanks for lunar gravity can then be fitted along with landing lidars.

How about a Dragon 2 with an extended trunk, as discussed in NSF, and a tanker stage in moon orbit?

Two launches, one for the tanker, and one for the Dragon2 with an extended trunk. The tanker is launched first into moon orbit. The Dragon 2 is launched, and uses a propulsion module fitted into the extended trunk to reach moon orbit. It refuels and lands. It takes off, refuels again, and returns to Earth.

This is a great thread. Rendezvous in LLO seems like a highly logical way to decompose the overall problem and allow two different efforts (perhaps one public and one private) to cooperate on the endeavor.

It leads to both halves of the solution (the crew capsule and the lander) addressing a shared propulsion challenge: lunar orbit insertion. It's a challenge because the propulsion system needs to function days after launch and with current technology that pretty much means hypergolic propellants which pretty much mean comparatively low Isp and thus higher (IMLEO) mass.

From Apollo we tend to think an AJ10 or similar engine is appropriate for this: 43.7 kN thrust; 319 s vac. Isp; 6 minute LOI burn duration. And gosh, Orion uses pretty much the same engine as Apollo. Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?

According to the Wikipedia entry the stated chamber pressure of the SuperDraco is 6900 kpa, which seems to suggest it would have a pretty high ISP with a much larger nozzle. I've been meaning to figure out what that might be but have a lot of "homework" to do on the matter to get an answer.

According to the Wikipedia entry the stated chamber pressure of the SuperDraco is 6900 kpa, which seems to suggest it would have a pretty high ISP with a much larger nozzle. I've been meaning to figure out what that might be but have a lot of "homework" to do on the matter to get an answer.

About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).

The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.

About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).

The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.

What nozzle diameter would be required? I'd like to put a rendering together for discussion purposes based off the known pressure vessel dimensions.

Also, what happens to the ISP if the SD's are ran at a lower throttle setting to allow for adequate expansion with smaller nozzles? At 71kN max thrust per engine even 4 SD's would be more than enough rather than 8.

If you are running sets of engines on both sides anyway why not launch the lander on its side and make it more rectangular? The cabin (or capsule) is in the middle and everything is disbursed to the sides including the equipment that would normally be under it that is part of the trunk. Hatch would be closer to the ground also. You would have do something creative to take the some of the load off of the side of the lander during launch.

About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).

The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.

What nozzle diameter would be required? I'd like to put a rendering together for discussion purposes based off the known pressure vessel dimensions.

Also, what happens to the ISP if the SD's are ran at a lower throttle setting to allow for adequate expansion with smaller nozzles? At 71kN max thrust per engine even 4 SD's would be more than enough rather than 8.

I get 110 kN and 343 seconds at 6.9 MPa and 140:1 expansion. The SuperDraco throat appears to be 0.100 m in diameter, so 140:1 expansion requires a 1.20 m diameter nozzle (which would be 1.68 m long for a 90% bell or 1.21 m long for a 65% bell that still gets 340 second ISP).

Vacuum ISP is mostly independent of chamber pressure (throttle): reducing pressure to 70% reduces ISP from 343 seconds only to 342 seconds, and going all the way to 20% throttle only reduces ISP to 336 seconds.

You can almost infinitely vary nozzle diameter and length to fit in various packages with different performance levels. Try downloading RPA lite and plugging some of these values in to see where the optimal nozzle is for your size requirements.

If you are running sets of engines on both sides anyway why not launch the lander on its side and make it more rectangular? The cabin (or capsule) is in the middle and everything is disbursed to the sides including the equipment that would normally be under it that is part of the trunk. Hatch would be closer to the ground also. You would have do something creative to take the some of the load off of the side of the lander during launch.

Edit: Maybe even use two trunks for the side structures on each side.

Use an sheet metal cylinder sidewall similar to F9 stage tank construction with no cant. Use the additional volume to allow more lower tankage w/o affecting crew volume. Isolate lines externally with MLI.

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Yes - which is why a Crasher Stage has been mentioned a couple times, in part so as to not make the Lander too tall.

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Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Small note: you have 3 engines shown in all the TWR calcs.What material did you assume for the tanks? SuperDraco mass?

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

SuperDraco is pressure-fed. Will those tanks hold 1000+ psi?

No. They are much too large. A 3m diameter COPV tank might just survive 1000 PSI. But without much safety margin, even with a 1 cm wall. The 5m dia. tank explodes.Back to the drawing board :-)

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Small note: you have 3 engines shown in all the TWR calcs.What material did you assume for the tanks? SuperDraco mass?

COPV, but that fails for large tanks. Need a less drastic engine.I also had 10T rather than 7, but that's not too bad. I think i'll illustrate three engines. 4 seems overpowered.

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

Yes - which is why a Crasher Stage has been mentioned a couple times, in part so as to not make the Lander too tall.

Could we soft land the crasher stage? Might be useful.How bad is a tall lander?

I guess the lander could separate in two just before landing, and land on the superdracos. We would need some extra fuel for lift off though. Perhaps we need three elements for the lander? I'll try another image.

Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?

SuperDraco is pressure-fed. Will those tanks hold 1000+ psi?

Unlikely. And, if they did, likely too heavy.

Such an approach argues for pump fed engines. Possibly electrically run (see upthread suggestion) off of high density Li-ion rechargables, as your burn times will be short, you've got excess array power, and sufficient recharge time between burns. So even better than Electron.

Now if the Dragon doesn't need any of the existing pressurized prop tanks and helium how much could it save?

I have been playing around with some numbers and shedding some weight have the total dry mass of everything at 5600kg (could be low), prop load at LLO required 15000kg, and using a 2.1m dia x 4.3m tank in place of the trunk so that the 4xsuperdraco vac engines can be tucked up under the pressure vessel, and not canted. This would require stripping out the existing propellant tanks that are stuffed under the widest part of the PV. The tanks could of course be laid out like a proton in between the SD's to save some height, but this would be less mass. It's just a sketch at the moment so go easy on me...

If you are running sets of engines on both sides anyway why not launch the lander on its side and make it more rectangular? The cabin (or capsule) is in the middle and everything is disbursed to the sides including the equipment that would normally be under it that is part of the trunk. Hatch would be closer to the ground also. You would have do something creative to take the some of the load off of the side of the lander during launch.

Edit: Maybe even use two trunks for the side structures on each side.

Use an sheet metal cylinder sidewall similar to F9 stage tank construction with no cant. Use the additional volume to allow more lower tankage w/o affecting crew volume. Isolate lines externally with MLI.

As a side note if you didn't have a capsule in the middle, you could put a flat platform instead and use it as a cargo only hauler. The ramp to unload would be minimal since you're still close to the ground.

Why are you launching 51 tonnes of hypergols? The Falcon upper stage is more efficient for TLI, and you don't need that much fuel after TLI.

I'm just using the 54 tonnes SpaceX spec to LEO as my baseline. The super draco with a vacuum nozzle seemed to give almost the same performance as the second stage Merlin, 345 ISP vs 348, might provide less boil off problems and would be a dedicated long range design, rather than a significant change to the Falcon upper stage. Unfortunately my propellant tank exploded under high pressure :-( So I'm looking for a new engine, or a turbo pump super draco design.

For the Falcon heavy payloads to beyond LEO, 13 T to Mars for example, is it the second stage operating for a longer time, or is a dedicated third stage required, rather like a telecommunication satellite?

If you wanted to do suit-ports, they could be on an inner bulkhead and stored there and protected by the outer hatch cover. Open back suit-port cover, climb in, open the outer hatch and unfold the ladder and descend the few steps to the surface...

That's a beautiful design! But what allows the MVac to restart successfully after a days-long cold soak during trans-lunar coast? Because ... kerolox doesn't do that?

Thanks, off the top of my head would be simple heater blankets and strip heaters powered off the solar arrays. Orientation toward the Sun would help as well and it would need to be tested in a space environment test chamber. I'm always open to suggestions!

As before, if you wanted to do suit-ports, they could be on an inner bulkhead and stored there and protected by the outer hatch cover. Open back suit-port cover, climb in, open the outer hatch and unfold the ladder and descend the few steps to the surface...

Total Lunar Lander Dry mass: 5800kg*Numbers marked as asterisk are guesses and need further research of confirmation, based off 10% prop mass of Dragon 2 for removed tanks.**Does anyone have any reference info on what I could expect Carbon fibre tanks to weigh?

At launch a Falcon Heavy could launch into a GTO transfer the D2 Lunar Lander without payload and a full prop load of 15,500 kg for a combined mass of 21,100kg. Arriving in LLO the lander would have 7500kg prop remaining with the remaining 6500kg to be transferred in orbit by Orion stack or separate transfer vehicle.

Tanks for a 15,500kg prop load are 1xN2O4 2m dia x 2.3m long & 4xMMH 0.87m dia x 2.3m longAn alternative to the cluster tanks would be a 2.1m dia and 3.7m long tank with common bulkhead

Not shown in the model are solar panels & ladder (among many other small details).

Total Lunar Lander Dry mass: 5800kg*Numbers marked as asterisk are guesses and need further research of confirmation, based off 10% prop mass of Dragon 2 for removed tanks.**Does anyone have any reference info on what I could expect Carbon fibre tanks to weigh?

At launch a Falcon Heavy could launch into a GTO transfer the D2 Lunar Lander without payload and a full prop load of 15,500 kg for a combined mass of 21,100kg. Arriving in LLO the lander would have 7500kg prop remaining with the remaining 6500kg to be transferred in orbit by Orion stack or separate transfer vehicle.

Tanks for a 15,500kg prop load are 1xN2O4 2m dia x 2.3m long & 4xMMH 0.87m dia x 2.3m longAn alternative to the cluster tanks would be a 2.1m dia and 3.7m long tank with common bulkhead

Not shown in the model are solar panels & ladder (among many other small details).

Nice work! Have you thought about if you lose one or more of the four SD's in flight? How do you abort? That's why I went with eight slightly over-expanded. You may not save all that much weight with carbon fiber tanks so I'm always open either way. You may want to put heat shields in the SD's exhaust plume impingement path or place the tanks above. Do you anticipate any payload to surface? Great modeling BTW!

If operated as a 1 way lander launched by Falcon Heavy expendable cargo to surface would be 2100kg.

With the superdraco thrust 3 engines is plenty but more losses due to gimballing would be incurred if one is lost.

As for impingement of exhaust, I was under the impression that with a very high expansion ratio to achieve the desired isp that this wouldnt be an issue. The F9 pictured is of sea level optomized engines at altitude. I wil read up more on that. However the engines can be gimballed out to 10 degrees without cosine losses becoming too significant. The 0 degree cant is required to fit in a faring during launch.

If operated as a 1 way lander launched by Falcon Heavy expendable cargo to surface would be 2100kg.

With the superdraco thrust 3 engines is plenty but more losses due to gimballing would be incurred if one is lost.

As for impingement of exhaust, I was under the impression that with a very high expansion ratio to achieve the desired isp that this wouldnt be an issue. The F9 pictured is of sea level optomized engines at altitude. I wil read up more on that. However the engines can be gimballed out to 10 degrees without cosine losses becoming too significant. The 0 degree cant is required to fit in a faring during launch.

There was some discussion in the AMOS-6 failure thread about the difference in tank material weight IIRC... I believe it was a post by HMXHMX, Don't forget your RCS... I guess you will be going with the Dracos... Wish I could model mine in your program, nice, keep at it!

The intent is that the dracos are in identical locations as D2 capsule (conformal pods between engines) modeling those would take some more effort. Some should definitely be added to the underside of the tanks however for improved attitude control and translational (strafe) movements.Program is Autodesk Fusion 360. Free trial, subscription service.

SpaceX has all the hardware pieces for a store-able prop Lander like the LM. It is a matter of the integrated vehicle design and software implementation to make it viable.

Meaning there is no long duration development program required to accomplish. A one way cargo mission using a Red Dragon design is possible (we believe it has > 2.5km delta V required to reach the Lunar surface). It would probably leave off the heat shield decreasing the dry weight and increasing the RD's design's delta V. So SpaceX has designs on the board right now capable of reaching the Lunar surface that can deliver multiple metric tons of cargo/payload. So now if that cargo payload was prop a series of two missions one a prop delivery to the surface. Includes the hardware to reach to another lander to refuel it. Possibly landed by a previous cargo landing such as a rover that has empty tanks that can move between the prop source and prop load destination. And the other a manned flight with a very small portion of the normal Dragon as living space (large enough for two people) that is then refueled on the surface that RD becomes a reusable LDRL (Lunar Dragon Reusable Lander) going back and forth between a Lunar orbit and the surface. Requiring 2 to 3 FH flights 1 to 2 that delivers all the prop for the descent and a LDT (Lunar Dragon Tanker) with prop for the ascent.

This then becomes an infrastructure that enables full support for a Lunar Base at the cost of - ~$500M per manned mission (includes the up to 3 FH flights of 2 carrying prop and a one way LDT)- ~$180M per one way cargo to surface carrying ~4mt of cargo- ~$250M per one way habitat delivery (this requires some new hardware designs that does not use a LD basic design modification but uses elements from it)

At a budget of $3B/yr could do:- 4 manned missions (continuous occupancy of 4 persons on surface at 6 month durrations)- 1 habitat expansion delivery or major cargo ~10mt of non-pressurized cargo (like a large manned enclosed rover that can do a sealed dock on the surface with the Lunar Dragons and habitats).- 4 pressurized supplies delivery ~3mt of supplies

This is a fully functioning and growing Lunar Base Program for the current SLS/Orion $3B budget.Other commercial providers could be a part of this as well for close to the same costs (Starliner, New Glenn, Vulcan/ACES/[Horizontal Lunar Lander], etc).

Edit Added:An additional note is that an an additional $1B for a total budget of $4B a Lunar Orbit station can be supported as well.- 2 X ~$180M/4 crew single flight to Station (with more of these could reduce the total cost of reaching the Lunar surface)- 3 X ~$130M pressurized cargo delivery to station- 1 X ~$220M station hardware expansion (includes the cost of the station expansion hardware (~$120M)

OK. Please look at OP of this thread. The focus is very narrow. Lets keep to it.

Yes it might enable more. Fine. But that isn't this thread. This thread is about doing something ... hard.

It's a hard, disciplined thing to take a CC vehicle, which we don't know much about (highly granular specs), and turn it into a dedicated lunar lander, in a few years (and I mean it) that could be used by a planned EM 1/2 mission (perhaps other/later). You get something around a billion or so to do this with. That's the challenge.

It does not need to be reusable. LM and LK certainly weren't. You get a bonus for a reusable lander or a plan leading to such. You can't burden dissimilar vehicles with co-integration, that's a no-no.

Here's the simplest expendable system - a Dragon for up, a Dragon for down, outfitted/integrated differently. Both require props/and engine enhancement. Requires precision landing. Requires LLO/direct descent props/pallet/stage (please note that Falcon 9/H had an optional third stage as PAM-D). You can mission plan it if you like. You'll find you'll need about 2k/sec delta-v addition for contingencies, which you can get in a variety of ways.

Like some of the additions this thread has come up with. Drop tanks - inside trunk, outside trunk, on capsule. Be careful you don't want to shade the PV panels. Or have plume impingement. The possibility of using electric pumps in place of pressurized tanks to a)lower tank mass, b) increase thrust/iSP, and c)reduce/reuse consumable pressurant. However, what would be the development time to make that as reliable as a pressurized escape system?

I've let things go a bit wider on this thread so you can gain involvement and promote some. Don't go too far.

The hard part here is coloring within the outline. Think small and tight. Can this be done in a few years at all?

If so, can it be done better? Can it lead to something ... where an aggressive follow-on program might develop its ambitions ...

OK. Please look at OP of this thread. The focus is very narrow. Lets keep to it.

Yes it might enable more. Fine. But that isn't this thread. This thread is about doing something ... hard.

It's a hard, disciplined thing to take a CC vehicle, which we don't know much about (highly granular specs), and turn it into a dedicated lunar lander, in a few years (and I mean it) that could be used by a planned EM 1/2 mission (perhaps other/later). You get something around a billion or so to do this with. That's the challenge.

It does not need to be reusable. LM and LK certainly weren't. You get a bonus for a reusable lander or a plan leading to such. You can't burden dissimilar vehicles with co-integration, that's a no-no.

Here's the simplest expendable system - a Dragon for up, a Dragon for down, outfitted/integrated differently. Both require props/and engine enhancement. Requires precision landing. Requires LLO/direct descent props/pallet/stage (please note that Falcon 9/H had an optional third stage as PAM-D). You can mission plan it if you like. You'll find you'll need about 2k/sec delta-v addition for contingencies, which you can get in a variety of ways.

Like some of the additions this thread has come up with. Drop tanks - inside trunk, outside trunk, on capsule. Be careful you don't want to shade the PV panels. Or have plume impingement. The possibility of using electric pumps in place of pressurized tanks to a)lower tank mass, b) increase thrust/iSP, and c)reduce/reuse consumable pressurant. However, what would be the development time to make that as reliable as a pressurized escape system?

I've let things go a bit wider on this thread so you can gain involvement and promote some. Don't go too far.

The hard part here is coloring withing the outline. Think small and tight. Can this be done in a few years at all?

If so, can it be done better? Can it lead to something ... where an aggressive follow-on program might develop its ambitions ...

Ok my opinion can a Crewed LF be done in a few years? 2 maybe. 3 definitely.

The 2 depends on no slips to FH or CC development programs. Something that cannot be taken for granted.

SpaceX has shown to be very sprightly when it comes to sophisticated software development accomplishing in months (3-9) what it takes others a few years. Adapting and modifying hardware designs is a similar thing 1/2 to 1/4 the time as others. But if the government is involved the time advantages seem to disappear. With this flight as long as there is no government strings attached other than FAA approval, the schedule is a definite achievable in 3 years or less. If it was a government paid for mission I would not expect a flight before 2020. It is not any different in actual hardware or software it is all that extra paperwork and approvals through the various steps that slow things down.

With the above mentioned, very likely an almost stock Dragon 2, and an enhanced Starliner, could either/both be turned into a dedicated lander, possibly even reusable.

But it would require a long lived in space propulsion system of considerable capability.

Could such a stage be possible in 1-3 years? My read on advanced in space propulsion suggests that ULA/ACES is 5+ years at best for this, and SX/BO have nothing on the board for this "distraction". Anyone ... else?

Could this be possible with Blok DM? Stage lifetime?

add:

Could this be the simplest lander concept? Something that puts the entire burden of propulsion shortfall on a propulsive stage?

So, how this would work is: stage initiates aggressive PDI to suborbital velocity trajectory, within a few miles of surface does braking burn to bring props usage to within lander's capabilities for mission, undocks lander, lander brakes to confirm engine operation otherwise redocks, stage does high-g ascent burn to recover orbital velocity and enter parking orbit.

Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip.

Xeus-ACES might be 5+ off, but Xeus-Centaur could be much sooner.

Gets the Lunar Dragon concept at least to the point where with moderate increases in ISP (canted, partially expanded nozzles) and a large increase in prop meet the ascent requirements.

Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip.

Xeus-ACES might be 5+ off, but Xeus-Centaur could be much sooner.

Nope. Masten is tied up with XS-1. ULA is at a point they can't afford any distractions.

That's what I was getting at.

And why I didn't remark about your earlier comment was that it was too desperate to be believed.

It's not about being worthy, it's about having enough operational experience to bring this off. Masten doesn't.

There are four US in active use on the globe that can be made to have on orbit lifetimes of weeks. Could be modified for the thermal environment. Can't take this further.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

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Gets the Lunar Dragon concept at least to the point where with moderate increases in ISP (canted, partially expanded nozzles) and a large increase in prop meet the ascent requirements.

Yes.

They are most of the way there already if you simply trim the Dragon's mass budget - remember that the LM needed a 5 year diet to make it to Apollo 11 - even Apollo 10's LM was too heavy!

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Nope. Masten is tied up with XS-1. ULA is at a point they can't afford any distractions.

That's what I was getting at.

And why I didn't remark about your earlier comment was that it was too desperate to be believed.

It's not about being worthy, it's about having enough operational experience to bring this off. Masten doesn't.

There are four US in active use on the globe that can be made to have on orbit lifetimes of weeks. Could be modified for the thermal environment. Can't take this further.

My comment was hand-waving for sure. However even with $2B as you proposed on page 1 to one of the commercial crew providers there are still going to be significant schedule and personnel allocation challenges. They all have full plates, so why draw the line at a crash program to modify an LEO capsule to a lunar lander vs a crash program to modify an US to a crasher stage?Masten is probably too small I agree, however ULA is downsizing so one could argue that they have ALL the necessary resources other than funding.

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Blue Origin didn't have a lot visible for a suborbital rocket and capsule, then one day it was flying.

Do you have any insider information on the progress of their biconic capsule?

I've tried researching that on the NASA CRS contracts and came up pretty empty, but that's typical for their level of secrecy. I know they want to use a composite PV that has had assistance but most other support went to New Shep.It isn't realistic to think that they have a complete crew vehicle all ready to go, however without knowing exact progress to date I don't think its fair for outright dismissal of something emerging in a 2-4 year time frame.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Blue Origin didn't have a lot visible for a suborbital rocket and capsule, then one day it was flying.

Do you have any insider information on the progress of their biconic capsule?

Suggest that you notice how much of there agenda "moves along", in public.

For them to advance to a NS business, they've already said they need to launch weekly. They haven't been launching weekly.

For them to advance to orbital capsule, they need to finish/operate a NS capsule, to then "move on" to orbital capsule.

Note, that all NG provider business they've talked about is big geosats. They've only shown fairings on NG so far.

And the lunar reference is cargo only. All of this is consistent.

Suggest BO is attempting to play "catch up" with Musk on the reusable LV side (makes sense because he doesn't want Musk to dominate that market), and that HSF follows after that 2-3 year program.

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I've tried researching that on the NASA CRS contracts and came up pretty empty, but that's typical for their level of secrecy. I know they want to use a composite PV that has had assistance but most other support went to New Shep.It isn't realistic to think that they have a complete crew vehicle all ready to go, however without knowing exact progress to date I don't think its fair for outright dismissal of something emerging in a 2-4 year time frame.

You can't hide an orbital HSF program. Trust me, the AF tried that and failed, with 25x Bezos resources.

He's not hiding an unmanned orbital program. You can look closely for the HSF parts and they are not there. Likely they will play catch up on the HSF part afterward.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

Ah yes, coming around full circle to earlier posts where I suggested Delta II US and Antares US (Castors)...The required propellant mass needs to be at least 5000kg for ascent vehicle alone even using Dragon 2's engines for partial dV. Some of the larger ATK motors may do it. So the D2 can be used for initial lift off and final burn to orbit where the solid kick motor provides the majority of dV.

More of a cludge, but makes for less "upgrading" of each component. Keeping with pressure fed smallish canted nozzles for Dragon2 and existing or slightly enlarged tanks.

I know I'm necroing a bit here, because this thread hasn't been active in ten months, but I've played around with this idea in the past and so this thread was quite interesting to me.

Falcon Heavy expendable is advertised at 63.8 tonnes to LEO, 26.7 tonnes to GTO (LEO+2.27 km/s), 16.8 tonnes to trans-Martian injection (LEO+4.3 km/s), or 3.5 tonnes to trans-Plutonian injection (LEO+8.2 km/s). For each case, the total dV provided by the upper stage can be calculated trivially using the rocket equation, using the stage dry mass of 4 tonnes, the propellant load of 107.5 tonnes, and the isp of 345 seconds.

As the payload mass decreases, the total amount of dV in the stage increases, as does the remaining dV in the stage after orbital insertion. Plotting leftover dV against total dV for a range of payloads produces a closely linear plot:

The equation for the linear trendline is y=0.72x + 3.25, by the way.

This allows us to estimate the total stage dV in the stage for any given BLEO destination, which in turn can be used to estimate the payload for that destination. TLI is 2.73 km/s beyond LEO, which gives us a total stage dV of 5.22 km/s. By the rocket equation, this means a propellant fraction of 78.67%, or a payload of 25.15 tonnes.

Of course, there are a few other options. What if the Falcon upper stage was modified to allow for extended restarts, as has been proposed a few times on this thread? It could, in theory, provide both the TLI burn AND the LOI burn, a total cost of 4.04 km/s. Our model predicts a total stage dV of 6.17 km/s, a propellant fraction of 83.88%, and a payload of 16.66 tonnes.

And, finally...perhaps the most ambitious idea of all: what if you used an even smaller payload and then used the Falcon Heavy upper stage as a crasher to drop a Dragon 2 right above the surface, where it could use its thrusters to hover and land? Well, that's 5.93 km/s beyond LEO, a total predicted stage dV of 7.54 km/s, a prop fraction of 89.23%, and a payload of 8.98 tonnes.

Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

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Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

The upper stage on today's Falcon Heavy has modifications to allow extended restart, though likely not in the week-or-more range. Doesn't mean it would be impossible, though.

If SpaceX didn't want to expend a whole Falcon Heavy, they could send up the lunar module on a Falcon 9 followed by a reusable Falcon Heavies with one simply having an IDA mated to the PAF, as proposed upthread. They would dock, and then the Falcon Heavy upper stage could then perform the TLI and LOI, which also means you don't need to man-rate the Falcon Heavy.

Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

Another solution just include third stage using storable propellants which would remove the need for a lot of the design changes on the FH second stage.

Having seen extended restart capability with FH, we can say an expendable Falcon Heavy should be able to deliver up to 15.2 tonnes direct to GEO.

I get more like 12-13 tons direct to GSO.

« Last Edit: 02/09/2018 02:45 PM by Robotbeat »

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Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

Another solution just include third stage using storable propellants which would remove the need for a lot of the design changes on the FH second stage.

Yes, that's one solution. But storables aren't going to get quite as much isp as the MVac, even factoring in boil-off. And while it's not quite as mass-efficient on the way there, since you're bringing along extra tankage, it means lower mass in LLO and thus both a lighter and more compact lunar spacecraft.